Aluminum - Aluminium and Its Alloys

8/6/2019 Aluminum - Aluminium and Its Alloys

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A L U M I N I U M A N D I T S A L L O Y S


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CALYPSO WORKS


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A L U M I N I U M

A N D I T S A L L O Y S

T H E I R P R O P E R T I E S , T H E R M A L T R E A T M E N TA N D I N D U S T R I A L A P P L IC AT I O N

BY

C . G R A R DLIEUTENANT-COLONEL D'ARTILLERIE

TRANSLATEDBYC . M. P H I L L I P S

(NATURAL SCIENCES TRIPOS, CAMBRIDGE)

AND

H . W. L. P H I L L I P S , B . A . ( C A N TA B , ) , A . I . C .(LATE SCHOLAROF ST. JOHN'S COLLEGE, CAMBRIDGE)


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T R A N S L A T O R S 1 N O T E

IN th is t ran sla t ion of Col . G rar d 's boo k on " Alu m inium an di t s Al loys / ' the or ig ina l t ex t has been adhered to , wi th theexcep tion of ce rta in of th e app end ices. Ce rtain of th e con-

dit ions of the French aeronautical specificat ions, dealing withsampling and identif icat ion of material , have not been con-sidered of sufficient interest to English readers to warranttheir inclus ion, but the c lauses deal ing wi th methods andresults of tests have been given.

The cent igrade scale of temperatures has been re ta inedth roughou t t he book .

In s ta t is t ics of a general natureas, for ins tance, in thecase of approximate ou tpu tthe tonne and ton have beenregarded as equ ivalen t . I n exact s ta t is t ic s , how ever, anaccurate convers ion has been made, and both se ts of values

given.Where pr ices are given, the ra te of exchange has been takenas twenty-f ive f rancs to the pound s ter l ing, whatever the dateof the stat ist ics in question.

The Tensi le Strength and Elas t ic Limit are expressed inki logrammes per square mil l imetre and in tons per square

inchat the express wish of the author, both se ts of valuesare g iven th roughout the book , in the tab les and d iagrams .

In the case of Hardness and Cupping Tests , no convers ionhas been a t tempted, the metr ical values being in general usein th is co un try. As regards Shock Re sis tance a lso , no con-

i h b t t t d O th C t i t th t


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v ii i A L U M I N I U M A N D I T S A L L O Y S

is not taken into considerat ion, but the Shock Resis tance isexpressed s imply by the energy, in foot-pounds, absorbed byimpact upon a test piece of s tandard dimensions.

Assuming that the conversion from ki logramme-metresper square cent imetre to foot-pounds is an ar i thmetical possi-

bili ty, the figures would sti l l not be comparable, as thenumerical value depends to a very great extent on the preciseform of the test piece employed, especially on the angle andradius at the foot of the notch, which is different in Britishand Continental pract ice.

The t ranslators would wish to express their thanks to

D r. A. G-. C. Gw yer, Chief M eta llu rg ist t o th e B ritis h Alu -min ium Co., Ltd . , for his valuab le ad vice a n d for his assis tancein the reading of proofs.

C . M . P H I L L I P S .

H . W . L . P H I L L I P S .WABRINGTON,

November,1920,


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A U T H O R ' S N O T E

FOR carrying out the numerous tes ts required for th is worwe have u t i li sed th e fo llowing Go vernm ent lab ora tor ies :

Le La bora to i re d 'Essa is du Conserva to ire n a t ion a l des Aret Metiers (chemical analyses, mechanical tests) .

Le L ab ora toire d 'E ssais de la M onnaie e t des M M aill(chemical analyses) .

L e L ab or ato ire de la Sect ion tech niq ue d e F Art i l ler(chemical analysis) .

Le L ab or ato ire de l 'A ero na ut iq ue de Ch&lais-Meud

(mechanica l tes t s and micrography) .Th e resu l t s , f rom which im po r tan t d educ t ions hav e bemade, possess , therefore , the greates t re l iabi l i ty.

W e m u st a l so th a n k th e fo llowing pr iva te lab ora tor ie s :

Les La bora to i res de la Soci6te Lo rra ine-D ie t r ich (het rea tmen t s and mechan ica l t e s t s ) ,

Les La bo rato ires de l 'Usine Ci t roen (me chan ical te s ts amic rography) ,for the readiness with which they have placed their staflE a


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I N T R O D U C T I O N

GENERAL ARRANGEMENT OF CONTENTS

T H E chief characterist ic of aluminium is i ts low density, beingsecond only to magnesium, and, for this reason, i t i s valuable

for aircraft . A lum ini um wou ld be ideal if th is l ightn ess couldbe combined wi th the mechanica l p roper t ies of the Fer rousmeta l s .

The ore , f rom which alumina, for the preparat ion of themeta l , i s ex t rac ted , i s wide ly d is t r ibu ted , and France i s

par t icu la r ly favoured in th i s respec t .W h a t e v e r t h e m e t h o d o f w o r k i n g a n d t h e r m a l t r e a t m e n t ,pure a luminium only possesses a low st rength, which prohibi tsi ts use for ar t ic les sub jecte d to grea t s t resses . F o rtu n at el y,cer ta in of the mechanical proper t ies of the metal can beimproved by the addi t ion of o ther cons t i tuents , and in someof th e a l loys th u s formed t h e den si ty is l i t t le cha ng ed . Th eseare the so-called l ight al loys, in which aluminium is a mainconst i tuent , and which can be divided into :

(i) Light al loys of low strength,(i i) Light al loys of great strength.

In o the rs , a lum inium is presen t in such sma l l qu an t i ty th a tthe a l loy loses i ts character is t ic l ightness , to the advantageof some of th e me chanica l p roper t ies . Th e m ost im po r ta n tare those in wh ich copp er is th e pr inc ipal co ns t i tue nt . Th esea re


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x ii A L U M I N I U M A N D I T S A L L O Y S

stress upo n those in which alu m iniu m is of m inor im po rt-ance .

Adopting the classi f icat ion here given, arbi t rary, no doubt ,but which, f rom the aviator 's point of view, has i ts value,s ince i t pu ts s ide by s ide th e propert ie s of l ightne ss an d s t re ng th,we shal l consequent ly arrange this work according to thefol lowing scheme:

Booh I.Aluminium, compris ing two par ts :P ar t I . Prod uct ion of a lum inium .Pa r t I I . P rope r t i e s of a lum in ium .

Booh II.Alloys of aluminium, compris ing three par ts :

P ar t I I I . L igh t a l loys for cas t ing purpo ses .P ar t IV . Ligh t a l loys of gre a t s t ren gth .P ar t V. H eav y a l loys of grea t s t ren gth .

Thr oug hou t , a large nu m be r of tes ts ha s been m ade oneach typ e . In par t icu lar, an exh aus t iv e s tu dy has been

carr ied out on the propert ies as funct ions of cold work andannea l ing , and on the hardness a t a ll t em per a tu res . Th erel iabi l i ty of the resul ts is guaranteed by the s tandard of thetes t ing labora tor ies , and by th e rep uta t ion of th e exper im enters .


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A L t T M I N I U M A N D I T S A L L O Y S

BOOK I I

ALLOYS OF ALUMINIUM_, PAOECLASSIFICATION 67

PART? III LIGHT ALLOYS OF ALUMINIUM FOB CASTING

PUBPOSES 71PART IVLIGHT ALLOYS OF GREAT STRENGTH . . . 87CHAPTKB

I. (a) VARIATION IN MECHANICAL PROPERTIES WITH AMOUNT OPCOLD WORK . . . . . . . . 89

(6) VARIATION m MECHANICAL PROPERTIES WITH ANNEALINGTEMPERATURE . . . . . . . . 91

II . QUISNCHING 96E fec t of Quenching Temperature . . . . . 95Kate of Cooling . . . . . . . . 1 0 1Agoing after Quenching . . . . . . . 1 0 3

II I. VARIATION I N MECHANICAL PROPERTIES WITH TEMPERATUREOF BEANNEAL AFTER QUENCHINa 110

IV. RE SU LTS or CUPPING TES TS AFTER VARYING TEERMAX TREAT-MENT 114

V. HAKDNESS TESTS AT HIGH TEMPERATURES . . . . 1 1 6

PART VCTJPHO-ALUMINIUMS OR ALUMINIUM BRONZES . 117

I. GENE RAL PROPE RTIES 118II . MECHANICAL PROPE RTIES 120

Alloy Typo I (90 % Cu, 10 % Ai) 121Alloy Typo II (80 % Cu, 10 % Al, 1 % Mn) . . . . 1 3 2Alloy Typo I I I (81 % Cu, 11 % Al, 4 % Ni, 4 % Fe) . . 137

1IJ. MICROGRAPHY . . 1 4 2

APPENDICESAPPENDIX

I. ANALY TICAL METHODS 147II- EXTBACTS IROM THE FRENCH AERONAUTICAL SPECIFICATIONS

FOR Al/UMINIUM AND LlGHT ALLOYS 03? GitEAT STRENGTH . 151

H I . RE PO RT OF TESTS CARRIED OUT AT THE CONSERVATOIRE DESA BT S ET METIERS ON THE COLD WORKING OF ALUMINIUM . 155IV . REPO RT OF THK TESTS CARRIED OUT AT THE CONSERVATOIRE DES

ABTS ET METIERS ON ANNEALING THIN SHEET ALUMINIUMAFTBR. COLD WORK 158

V. B E P O B T O F TESTS CARRIED OUT AT THE CONSERVATOIRE DESAB TS ET METIERS ON THE ANNEALING or THICK (10 in .)SH BB T ALUMINIUM AFTER COLD WORK . . . . 1 6 7


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L I S T O F P L A T E S

Calypso Works Frontispiece

BOOK IALUMINIUM

PART IPRODUCTION .AOSTD METALLURGYPLATE TO FACE PAGE

I Norwegian Nitrides and Aluminium Company . . . . 1Photograph 1. Works at Eydehavn near Arendal

2. Works at Tyssedal on the Hardanger FjordII. Saint Jean de Maurienne . . . . . . . 1 3

Photograph 1. Cylindrical dam 2. Aqueduct across the Arc

III. Engine-room at Calypso . . . . . . . 1 3

PART IIPROPERTIES or ALUMINIUMI ANDII. Micrography of Aluminium . . . . . . 5

Photograph 1. Aluminium ingot, chill cast (K. J. Anderson) 2. Aluminium ingot, sand cast (R. J. Anderson) 3. Aluminium, cold worked (50 %) 4. Aluminium, cold worked (100%)

5. Aluminium, cold worked (300 %) C. Aluminium, cold worked (300%) and subsequentlyannealed at 350 for 10 minutes

7. Aluminium annealod at 595 for 60 minutes (R. J .Anderson)

8. Aluminium annealed at 595 for 4 hours (R. J .Anderson)


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PABT VCUPRO-ALUMINIUMSI. Micrography of cupro-almninium, Type I, forged and annealed 143

Photograph 1. As forged. x 60 2. As forged. X225 3. Forged and subsequntly annealed at 300.

X60 4. Forged and subsequently annealed at 300.

X225I B . Micrography of cupro-alummium, Type I, showing eutectic

structure . . . . ' . . . . . 1 4 3Photograph A. Etched with alcoholic FeCl3. X 500

(Portevin) B. Etched with alcoholic FeCl3. X 870

(Portevin) C. Etched with alcoholic FeCl3, showing cellular

and lamellar formations. x500 (Por-tevin) D. Etched with alcoholic FeCl3, showing eutectic

+ 7. Hypereutectoid alloy. X200(Portevin)

II. Micrography of cupro-aluminium, Type I, forged and subse-quently annealed. . . . . . . . 1 4 3

Photograph 5. Forged and subsequently annealed at 700.

X60 G. Forged and subsequently annealed at 700.X225

7. Forged and subsequently annealed at 900.X60

8. Forged and subsequently annealed at 000.X225

III . Micrography of cupro-aluminium, Type I, forged and subse-

quently quenched . . . . . . . 1 4 3Photograph 9. Forged and subsequently quenchod from500. xCO

10. Forged and subsequently quenched from500. X225

11. Forged and subsequently quenched1 from600. x 60

12. Forged and subsequently quenched from

600. X225IV. Micrography of cupro-aluminium, Type I, forged and eubso-quently quenched (Breuil) . . . . . . 1 4 3

Photograph 13. Forged and subsequently quenchod from700. x (50

14. Forged and subsequently quenched from700. x 225


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L I S T O F P L AT E S xvi iPLATE TO PACE PAGE

V. Micrography of cupro-aluminiura, Type I, forged and subse-quently quenched (Breuil) . . . . . . 1 4

Photograph 17. Forged and subsequently quenched from

900. X 60 18. Forged and subsequently quenched from900. X225

VI. Micrography of cupro-alumiraium, Type I, forged, quenched,and reannealed . . . . . . . . 144

Photograph 19. Forged, quenched from 900, reannealed at

300. x 60 20. Forged, quenched from 900, reannealed at300. X 225

21. Forged, quenched from 900, reannealed at600. x 60

22. Forged, quenched from 900, reannealed at600. x 225VII. Micrography of cupro-aluminium, Type I, forged, quenched,

and reannealed . . . . . . . . 1 4 4Photograph 23. Forged, quenched from 900, reannealed at

700. X 60 24. Forged, quenched from 900, reannealed at

700. X 225 25. Forged, quenched from 900, reannealed at800. X 60

26. Forged, quenched from 900, reannealed at800. x225

VIII. Micrography of cupro-aluminium, Type I, cast and annealed . Photograph 27. As cast. x 60

28. As cast. x225 29. Cast and annealed at 800. X 00 30. Cast and annealed at 800. X 225

IX . Micrography of cupro-aluminium, Type I, cast and annealed .


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Micrography of cupro-aluminium, Type II, quenched and re-armealed . . . . . . . . . 14.4.

Photograph 42. Quenched from 900, rearmealed at 600.X60

43. Quenched from 900&, reannealed at 600.X225

X I I I . Micrography of cupro-aluminrum, Type I I I , forged and an-nealed . . . . . . . . . 144

Photograph 44. As forged. xCO45. As forged. x 225

46. Forged and annealed a t 600. y 60 47. Forged and annealed at 600. x 225

X IV . Micrography of cupro-aluminium, Type III , forged and an-nealed . . . . . . . . 144

Photograph 48. Forged and annealed at 800. x 60 49. Forged and annealed a t 900. x 225

XV. Micrography of cupro-aluminium, Type II I, forged andquenched . . . . . . . . . 144

Photograph 50. Quenched from 500. x 60 51 . Quenched from 500. x225 52. Quenched from 800. x60 53 . Quenched from 800. x225

X V I. Micrography of cupro-aluminium, Type III , forged andquenched 144

Photograph 64. Quenched from 900. X 6055. Quenched from 900. x225

X V II . Micrography of cupro-alumiaium, Type I I I, quenched andreannealed 144

Photograph 56. Quenched from 900, reannealed at 500.X60

57. Quenched from 900, reannealed at 500*.X225

58. Quenched from 900, reannealed at 600.X60

59. Quenched from 900, reannealed. a t 600.

X225


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BOOK I

ALUMINIUM

PART IPRODUCTION AND METALLURGY

FIGURE PAGE1. Melting-point curve of mixtures of cryolite and alumina . . 52. World's production of bauxite . . . . . . 93. Map of the South of France, showing distribution of bauxite and

situation of aluminium and alumina factories . . . 1 1

PART IIPROPERTIES4. Variation in mechanical properties (tensile) of thin aluminium

sheet (1 mm. thick) with cold work . . . . . 235. Variation in mechanical properties (tensile) of thick aluminium

sheet (10 mm. thick) cut longitudinally to the direction ofrolling, with cold work. . . . . . . . 2 6

6. Variation, in mechanical properties (tensile) of thick aluminiumsheet (10 mm. thick) cut transversely to the direction of rolling,with cold work . . . . . . . 27

7. Variation, in mechanical properties (tensile) of aluminium withannealing temperature. Test pieces 0-5 mm. thick. Prior cold

work 50 % 288. Variation in mechanical properties (tensile) of aluminium withannealing temperature. Test pieces 0-5 mm. thick. Prior coldwork 10 0% 29

9. Variation in mechanical properties (tensile) of aluminium withannealing temperature. Test pieces 0*5 mm. thick. Prior coldwork 300 % 30


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12 Variation in mechanical properties (tensile) of aluminium withannealing temperature. Test pieces 2-0 mm. thick. Prior coldwork 300 % 3

13. Variation in mechanical properties (tensile) of aluminium with.annealing temperature. Test pieces 10 mm. thick. Prior coldwork 100 % 35

14. Variation in mechanical properties (tensile) of aluminium withannealing temperature. Test pieces 10 mm. thick. Prior cold

work 300 % 3615. Variation in mechanical properties (hardness and shock) with coldwork. Test pieces 10 mm. thick . - . . . . 3 7

16. Variation in mechanical properties (hardness and shock) on anneal-ing after 100 % cold work. Test pieces 10 mm. thick . . 39

17. Variation in mechanical properties (hardness and shock) on anneal-ing after 300 % cold work. Test pieces 10 mm. thick . . 40

18. Persoz apparatus for cupping tests 4219. Cupping tests. Variation in breaking load and depth of impressionwith cold work. Test pieces 2-0, 1-5, 1-0, 0-5 mm . thick . . 43

20. Cupping tests. Variation in breaking load and depth of impressionwith thickness at specified am ounts of cold work (0, 50, 100,and 300 % ) 44

21. Cupping tes ts . Variation in breaking load and depth of impressionon annealing after 50 % cold work. Test pieces 0-5 mm. thick 45

22. Cupping tes ts . Variation in breaking load and depth of impressionon annealing after 100% cold work. Test pieces 0-5 nun. thick 46

23. Cupping te st s. Variation in breaking load and depth of impressionon annealing after 300 % cold -work. Test pieces 0-5 mm . thick 47

24. Cupping tes ts . Variation in breaking load and depth of impressionon annealing after 50% cold work. Test pieces 2-0 mm. thick 48

25. Cupping tests. Variation in breaking load and depth of impressionon annealing after 100 % cold work. Test pieces 2-0 mm. thick 49

26. Cupping te sts. Variation in breaking load and depth of impressionon annealing after 300% cold work. Test pieces 2-0 mm. thick 50

27. Cupping tes ts. Variation in depth of impression with thickness.Annealed aluminium sheet (R. J". Anderson) . . . . 5 3

28. Cupping tests . Variation in depth of impression with thickness.Cold worked aluminium, sheet (R. J. Anderson) . . . 54

29. Aluminium sheet. Effect of annealing for different lengths oftime a t 430 (R. J. Anderson) 55


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1 I S T O F I L L U S T E AT I O N S I N T E X T x x i

BOOK I I

ALLOYS OF ALTJMINIUMT-i - PA.GEiL.q_u.ili"briuin diagram of copper -aluminium alloys (Curry) . . 69

PART IIICASTING ALLOYS*> H a r d b ie s s of aluminium at high temperatures (500 kg. load) . 73

"archness of aluminium-copper alloy(i % Cu) at high tempera-"tixxes (50Oand 1000 kg.) 77

** * -Ha,r


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FIGTOBE67. Variation in mechanical properties (tensile and impact) with an-nealing temperature. Forged aluminium bronze, Type I . 1 2 4

68. Variation in mechanical properties (tensile and impact) withquenching temperature. Cast aluminium bronze, Type I . 1 2 5

69. Variation in mechanical properties (tensile and impact) withquenching temperature. Forged aluminium bronze, Type I . 126

70. Variation in mechanical properties (tensile and impact) withtemperature of reanneal after quenching from 700. Forgedaluminium bronze, Type I . . . . . . . 127

71. Variation in mechanical properties (tensile and impact) with.temperature of reanneal after quenching from 800. Forgedaluminium bronze, Type I . . . . . . . 128

72. Variation in mechanical properties (tensile and impact) with

temperature of reanneal after quenching from 900. Forgedaluminium bronze, Type I . . . . . . . 120726. High-temperature hardness tests (500 kg.) on aluminium bronze,

Type I, as cast, worked, and heat treated . . . . 1 3 173. Aluminium.bronze, Type II , critical points . . . . 13274. Aluminium bronze, Type I I . . . . . . 1 3 275. Variation in mechanical properties (tensile and impact) with

annealing temperature. Forged aluminium bronze, Type I I(Cu 89 %, Mn 1 %, Al 10 %) 133

76. Variation in mechanical properties (tensile and impact) withquenching temperature. Forged aluminium bronze, Type I I . 134

77. Variation in mechanical properties (tensile and impact) with.temperature of reanneal after quenching from 800. Forgedaluminium bronze, Type I I . . . . . . . 135

78. Variation in mechanical properties (tensile and impact) withtemperature of reanneal after quenching from 900. Forgedaluminium bronze, Type I I . . . . . . . 1 3 5

78b.High-temperature hardness tests (500 kg.) on aluminium bronze,Type II . Quenched from 900, reannealed at 600. . . 1 3 6

79. Aluminium bronze, Type III , critical points (dilatometer) . . 13780. Aluminium bronze, Type III, critical points, temperature time

curve . 13881. Variation in mechanical properties (tensile and impact) with

annealing temperature. Forged aluminium bronze, Type I I I( C u 8 1 % , N i 4 % , F e 4 % , A l l l % ) 1 3 8

82. Variation in mechanical properties (tensile and impact) with.quenching temperature. FoTged aluminium bronze, Type I I I 139


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A l u m i n i u m a n d i t s A l l o y s

PA RT I

P R O D U C T I O N O F A L U M I N I U M

C H A P T E R I

METALLURGY OF ALUMINIUM

ALUMINIUMi s pre par ed by th e e lec tro lys is of a lu m in a d issolvedin fused cryo li te . Th e electr ic energ y is de rive d from w ate r-power. Th e essent ia l m ater ia ls for th e process are th eref ore

( i ) Alumina ,(ii) Cryolite.

A L U M I N A .Alum ina is pre pa red f rom b au xi te [ (Al , F e)2 O 8 2 Ha O] o r

f rom cer ta in c lays [Al2O3.2SiO2] .(a ) From Bauxite.

Ba ux i te is a c lay- like sub s tanc e , whi t i sh wh en s i lica is pre -dom inant , or reddish whe n oxide of i ron i s la rgely pr es en t . I ti s found in g rea t quan t i ty in F rance , in the ne ighbourhood o fthe v i l lage of Baux, near Ar ies (hence the name, bauxi te) ,an d more com mo nly in the D ep ar tm en t s of B ouch es -du-Rh one , Ga rd , Ar iege , H6 raul t , and Va r. I t is foun d in Calabr ia ,Ice land, S tyr ia , Carniola , and in the Uni ted Sta tes of Americain Georgia , Arkansas , Alabama, and Teimessee .

Commercia l bauxi te has the fo l lowing composi t ion :*Alumina (A12O8) . 57 % A pr em iu m of -20 t o -40 franc s

per ki lo (roughly Id. to 2d. perlb.) was, in 1909, paid for eachper cent over 60 %.

Silica (SiOa) . . 3 % If below 2 % , a p re m iu m of -20fr. per k g. (roug hly I d . pe r lb.)was pa id per -1 % .


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4 ALUMINIUM ANDIT S A L L O Y S

Iron Oxide (Fe2O 3) . 1 4 % Fo r each per cent abo ve th isva lue , up to the max imumallowed, 17 % , -20 fr. p er k g .(roughly Id. per lb.) was de-ducted. Some wo rks al low asmu ch as 25 % Fe2 O 3 .

White bauxites are chiefly used for the production ofaluminium sulphate and the alums. R ed ba ux i tes form th eraw material for the preparation of alumina, and therefore ofaluminium . Interm ediate or refractory ba ux i tes , fused in anelectric furnace, give artificial corundum.

Bauxite is treated either by Deville 's method or by that ofBayer, th e lat ter being almost exclusively em ploy ed. A t hi rd

method depends upon the product ion of a lum inium ni t r ide .This is obtained by heating bauxite in air to 1800-1900 inan electric furnace. I t is then decomposed in an au toc lav e inpresence of soda solution, giving (i) ammonia, used as a manurein the form of i ts sulphate, (ii) sodium alu m ina te, from wh ichcommercially pure alumina can be obtained.

(b) From Clay.Clays are treated either by the Cowles-Kayser or by the

M oldentrauer process, yielding alum ina from w hich alu m ini umis prepared by electrolysis.C RY O L I T E .

Cryolite, which is so called on account of its high fusibility,is a dou ble fluoride of alum inium an d sodiu m of th e for m ulaA l2F6.6N aF. I t i s obtained from Western Green land, whe reit occurs in beds up to one metre thick, but the high price ofthis material has led to the manufacture of synthetic cryolite,using calc ium fluoride (fluor-spar), which is fo un d in con-siderable quantit ies.

E L E C T B I C F U R N A C E S .

The furnac e consists of a va t, containing elec trodes (ano des),and a conduct ing hear th ( the cathode) s loping towards thotap pin g hole. Aluminium, formed by electrolysis of t h ealum ina, collects on the floor of the v a t ; oxyg en is l ibe rat edat the anod e, which i t a t tacks , forming carb on m ono xid eand finally carbon dioxide.

Th t i d t t ti l diff f 8 t 10


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M E TA L L U R G Y O F A L U M I N I U Mth e lat te r is pr es en t in sm all qu an t i t ie s , th e fluorides dec om -pose , an d th e vo l tag e (no rm ally 8-10 vol ts) r ises . T his isindica ted b y th e chan ge in in ten s i ty of a la m p . I n th i s casesodium is form ed at th e cath od e, a n d h as d elete r iou s effectson the qual i ty of the meta l .

M E T H O D O P TA P P I N G A L U M I N I U M .

Since alum iniu m is ve ry easi ly oxidised, i t ca n n o t be su b -jected to a f inal refining process , b u t m u st p ossess , a t th is e ar lystage, i ts com m ercial p u ri ty . I t is therefo re essent ial to av oidoxidat ion dur ing the manufactur ing process , and the cryol i te ,

1000-

9 7 5

950-

925-

900-

0 5 10 15 2 0

F I G . 1 . M e l t i n g - p o i n t C u r v e o f M i x t u r e s of A l2 F f l . C N a F a n d A 12 O 3 . (Pryn.)

c o n t a i n i n g a l u m i n a i n s o l u t i o n , f u r n i s h e s t h e m e a n s t o t h a t

e n d . T h e m e t a l l i c a l u m i n i u m m u s t n o t float, b u t s i n k t o t h e

b o t t o m o f t h e v a t , w h e r e t h e f u s e d s a l t s p r o t e c t i t a g a i n s t

o x i d a t i o n . T h e s a l t s m u s t h a v e , t h e r e f o r e , a l o w e r d e n s i t y

t h a n t h e m e t a l .


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6 A LT J m N I U M AND ITS A L L O Y S

Certain definite mixturesof cryol i te , ca lc ium f luor ideoraluminium fluoride, and alumina have s t i l l lower mel t ingpo in t s , the l imit ing value being 800 (Hall) .In prac t i c e themel t ing po in tof the bath ranges f rom 900-950; it is t h e r e -fore evident that the manufacturer has a choice of m i x t u r e swhich will fulfil these conditions.

The respective densit iesof the cryo l i t e mix ture and ofa lumin ium a re :

Cryol i te mixture

Alumin ium .

l l iqu id ,/ so l id ,l l iquid ,

2-922-082-62-54

which satisfythe condi t ions above ment ioned.

T&LJurnace is t apped about every fo r ty -e igh t hours .Th eliquid flows first intoa receiver, in which t he f luor ides carr iedover are re ta ined in the solid state, and f rom this vessel in tomoulds, giving ingots whichcan easily be d iv ided .

O U T P U T.

According to Flusin , the ou tpu t is as follows :

210 kg. to 275 kg. of aluminium per k i l o w a t t - y e a r(i.e. 4 6 3 l b . - 6 0 6 - l l b .per kw. year ) ,

or, 154-200 kg. per " Force de c h e v a l" y e a r(i.e. 344-1-447lb. per horse-power year) ,

which works out at :31-41 ki lowat t hoursper kg. of a lumin ium

(i.e. 14-1-18-7 kw. hours per lb.),assuming an average efficiency of 70 %, a nd a m a x i m u mefficiency of 78 %.

C O N S U M P T I O N OF M AT E E I A L .

Aluminaper kg. of aluminium : theoret ical ly 1*888 kg.prac t ica l ly 2-0 kg . ;

formerly this figurewas higher, but t hen t he vo l t age was 15t o 20 v. (i.e. 1*888 tons and 2-0 t ons of a l u m i n a per ton ofaluminium, respect ively) .

Cryoli te, per kg. of a lumin ium 0-150 kg. on an a v e r a g e(i .e. 3 cwt. cryol i te per ton of a lumin ium) .

Calcium and aluminium fluorides, per kg. of a l u m i n i u m ,0 200 k (i 4 f l i i )


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M E TA L L U R G Y O F A L U M I N I U M

From these da ta we can draw the fo l lowing conc lus ions con-cerning th e cost pr ice . F or th e pr od uc t ion of a to n of a lu-minium two tons of a lumina a re requi red and a l so one ton ofcarbon for th e e lectrodes ; whi le , for th e pro d uc t io n of th ea lumina itself, s ix ton s of carbon a re requ i red . S ince a lum inais made near the spot where bauxi te i s found , i t i s necessaryto consider the effect of the fol lowing t ransport charges uponthe cos t p r ice :

(i) Carr iage of carbon to a lumina works ,( i i ) Carr iage of carbon to a luminium works ,

( i i i ) Carr iage of a lumina to a luminium works .

I t is ev iden t t h a t t hose a lumin ium w orks wh ich can ob ta inonly hydrau l ic pow er loca lly, so th a t the t ra n sp o r t cha rges ,jus t ment ioned , a re heavy, a re a t a d i sadvantage in compet ingwi th works mo re f avourab ly s i t ua t ed . Th e F r en ch a lum in iumworks are especial ly favoured in this respect .*

R O L L I N G O E A L U M I N I U M : .

Th e ingots of a lu m iniu m are firs t m el t ed in a furn ace oftena revolv ing furnace , he a te d b y gaseous fue l. T h e a lu m iniu mis th en cast in to s labs , wh ich, in F ra n ce , us ua l ly ar e of th efol lowing dimensions:

(1) 80 k g .= 0 -5 5 m . X 0-65m. x 0-08m.(21-6in. X 25-5in. X 3-15in.)

(2) 55 k g .= 0 -5 6 m . X 0-66m. x 0-055m.(22-0in. X 25-9in. X 2-16in.)(3) 27kg .=0-35m. xO-7m. xO-O4m.(13-8 in . x27-5 in . x l -57 in . )

* Lodin established in the following manner the cost price in 1909 :Alumina . 1 -950 kg. per kg. of Al at 0-3 fr. per kg. . 0-585 fr.Cryolite . . 0125 kg. 0-6 . 0-075,,Electrodes . 0-800 kg. 0-35 . 0-280,,Labour . . 0025 5 0125 ,,Electrical energy 40 kw. at -006 fr. per kw. . 0-240

Total . l-305fr.per kg. of aluminium (i.e. roughly 6d. per lb.), to which, in general, transportcharges must be added.

In the United States of America, the cost price of aluminium in 1906would be, according to "T he Mineral Industry ," roughly 7Jd. per lb. Theprice of aluminium has varied in a very noticeable manner since 1855 having


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8 A L U M I N I U M A N D I T S A L L O Y S

Aluminium is often cast into bil lets , frequently cylinders of3 kg. in weig ht , 80 cm . high an d 4 cm . in diam ete r (31-5 in. X1-57 in.) . Th e slabs or bi l lets are ca st from a mi xt ur e of ingo ts,and therefore a fresh analysis must be carried out to give thequal i ty.

The temperature of cas t ing is usual ly 750-775 , and thetem pera tu re of ro l l ing 400-450 , roughly the t e m pe ra tu re ofsmoulder ing wood.

B O L L I N G O F A L U M I N I U M I NT O T H I N S H E E T S . *

A lum inium ca n be rolled into sh eets -01 cm . th ick (*0039 in.) ,s imi lar to t infoi l . Th e process has been carr ied out by D roui l ly a s tr ip ini t ial ly 0-35 cm . thic k (-138 in.) is rol led in t h e coldto 0 -04cm. ( - 01 6 in . ) ; the reduc t ion i s m ade in s ix passeswith in te rm ed iate anneal in g. T he second s tag e consis ts in

reducing th e shee ts to a th ick ness of -01 cm. , e i ther b y m ean sof b lows f rom a 150 kg . ( roughly 3 cw t . ) pn eum at ic ha m m er,giving 300 blows per minute , or by fur ther ro l l ing.

E X T R U S I O N .

Tub es and se ct ions can be obta in ed by extru s ion, f

A L U M I N I U M D U S T.

Powdered a lumin ium, in the fo rm of pa in t , i s app l ied tofinished metall ic goods, result ing in a galvanisat ion effect .For l i tera ture on th is subject , the work of Gui l le t ( loc . c i t . )should be consul ted .

* For details of process, see Gurllet, "Progr6s des Metallurgies autrequela Side*rargie et letir 6 ta t acfruel en France," pp. 264-268. (Dunod et Pinat,

1912.)t Cf. Breuil, " G6nie Civil," 1917. Nos. 23 and 24.


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C H A P T E R I I

WORLD'S PRODUCTIONI . B A U X I T E .

T H E French Minis ter of Commerce g ives the fo l lowing pa

t i cu la r s concern ing the wor ld ' s p roduc t ion o f baux i te :*

1910191119121913

U.S .A .

To n n e s

152,070158,107162,685213,605

To n s

149,698155,610160,110210,228

F r a n c e

To n n e s

196,056254,831258,929309,294

To n s

193,358250,800254,836304,410

G r e a t B r i t a i n

Tonnes

4,2085,1035,8826,153

To n s

4,1425,0225,7896,056

I t a l y

Tonnes

6,952

To n s

6,842

I t i s therefore evid en t th a t u p to 1914, th er e were only twimpor tan t cen t res in the wor ld fo r the p roduc t ion o f baux iname ly, F rance and the Un i t ed S t a t e s o f Amer i ca .

P O S I T I O N I N 1 91 3.The dis t r ibut ion of bauxi te in 1913 (527,536 tons) i s sho

in the fo l lowing d iagram (Kg. 2 ) :

S c a l e10,000Tons

U.S.A.210,228 tons

I t a l y6 8 4 2


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Sixty-f ive per cent of the French product ion was expor ted ,half of which (i.e. 32%) was sent direct ly or indirect ly toG erm any , app rox ima te ly 15 % to G rea t Br i t a in , an d a ce rta inproport ion to the United States, which is rapidly fal l ing off , asth e new b eds a re deve loped in tha t co un t ry , in Tennessee andNor th Caro l ina .

Of th e 7365 to n s (7483 tonnes ) of alu m ina e xp or ted , 80 %goes to supply the Swiss factories.The Report of the French Minister of Commerce ( loc. ci t . )

shows the inf luence of the war on the product ion of bauxi te .

ka) France.

191519161917

Bauxite forAluminium

Tonnes37,89468,866

101,748

Ton37,29667,779

100,150

Bauxite forother purposes

Tonnes48,62837,33419,168

Tons47,86036,74318,865

TotalTonnes86,522

106,200120,916

Tons85,156

104,520119,015

Th e dim inut io n in prod uct io n is c lear ly due to th e large fal lingoff of exports.(b) United States.

1915 .1916 .1917 .

(c) Great Britain.1915 .1917 .

293,253 tons (297,961 tonnes ) of bau xite.418,640 (425,359 )559,750 (568,690 )

11,726 tons (11,914 tonnes) of bau xi te .14,714 (14,950 )

The whole of this amount was imported from the French bedsat V ar. Th e discovery of beds in Br itish Guian a, where thereare large waterfalls, will probably affect the British productionvery considerably.(d) Italy.

Position unchanged.

(e) Germany.Germany has been unable to import French bauxite and


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M E D I T E / I R A N I A NS A SCALC OF MILES{0 0 ^0 20 ^0 40

Reduction WorksPreparation of Alumina - - _ - - - - - _

iod

Fia. 3.Map of South of Franco,, to ahow distribution of Bauxite and situation ofAlumina and Aluminium Works.


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12 A L U M I N U M A N D I T S A L L O Y S

(20,000,000 tons) were discovered in Hungary (Siebenbergen).The bauxi te was sent to Germany, and works wore erected,on the sp ot , for t reat in g the m ineral . I n add i t ion , th ere aremines in D alm at i a , Herzegovina, Is t r ia and Cro at ia , whichare ei ther bein g w orke d or are rea dy to be w ork ed. Th e qu ali tyof this bau xi te seems on th e whole ve ry inferior to t h a t of th eFrench .

I I . A L U M I N I U M .A st at em en t of produ ction f igures can only be ma de w ith

caut ion, d iscr iminat ing between possible and actual output .T he la t t er, a f ract ion of the former, depend s upon the de m an d,

and also upon the possibil i ty of obtaining materials for theproduct ion of o ther substancesfor ins tance, the manufactureof aluminium replacing that of chlorates, and conversely.

Statistics, from this point of view, are often lacking in clear-ness . Nevertheless , bear ing in mind these two considerat ions ,we can consider the following figures as sufficiently accurate,referr ing to an average annual product ion.

(a) France.Pran ce, as is show n in the accom panying m a p (Fig .$), is

favourably s i tuated for the product ion of a luminium. Theclose pr ox im ity of th e b aux i te "beds, th e a lu m in a wo rks , a ndth e w ater po w er necessary for th e electro -m etallurg y, form s a

unique com bin at io n, and, in addi t ion, car bo n can be eas ilyconveyed to the works*A ct ua l ou tpu t , 12 ,000-15 ,000 ton s per an nu m .Po ssible ou tpu t , 18,000-20,000 ton s per an nu m .

A L U M I N I U M W O R K S .

Th e F re nc h w orks are am algam ated, forming " L1Alumin iumfrangaise ," and are grouped into companies :

(i) T he " S o c i t6 !5lectro-m6taUurgique franp aise," withworks a t P r a z , a n d a t S t . Michel de M aurienne in th e val ley ofthe Arc, and a t Argent iere in the val ley of the Durance.

(ii) T he " C om pag nie des P ro du its chim ique s (TAlaiB c t d e

PLATE I.


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PHOTOGRAPH 1.NORWEGIAN NITRIDES AND ALUMINIUM COMPANY.Works at Eydehavn near Arendal (25,000H.P.), situated on an arm of the sea.

PLATE IT.


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SAINT-JEANCYLINDRICAL DAM.


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PLATE III.

ENGINE-ROOM AT CALYPSO.


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W O R L D ' S P R O D U C T I O N IS

A L U M I N A W O K K S .

The a lumina works a re s i tua ted near the bauxi te beds H e r a u l t , Va r, a n d B o u c h e s - d u - R h o n e , a t G a r d a n n e a n d LBarasse (Bouches-du-Rhone) and a t Sa l indres (Gard) .

(b) Great Britain.Outpu t abou t 6000 tons .

There are two companies :(i) T he Br i t i sh A lum in ium Co m pany (Sco t land an d N orw a

(ii) The A lum in ium C orpora t ion (works a t D olgar ro g , N oWales ) .

(c) Italy.Outpu t 1500-2000 tons .

(d) Switzerland.O utp ut 12 ,000-13 ,000 ton s , f rom work s a t N eu ha us(canto n of Schaffhausen) a n d a t Chippis an d M ar t ig ny (c anof Vala is ) . I t i s no t iceab le t h a t in Sw itzer la nd th er e ar e works fo r th e p r ep ar a t io n of a lum ina f rom b au xi te , hen ce m ate r ia ls requ i red fo r th e m anu fac tur e of a lu m in iu m , a lu mand c ryo l i t e a re impor ted .

(e) Norway.T h e N o r w e g ia n o u t p u t h a s b e e n :

1913 . . ap pr ox im ate ly 1000 to n s

1917 . . 7000 1918 . . 6000

I t s poss ib le p ro du c t io n m ay be ab o ut 15 ,000-16 ,000 toAlum ina is im po r ted m ain ly f rom t h e work s a t Menes(Somme) an d Salzae te (Be lg ium ) be longing to L ' A lum in i


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of Canada, having thei r main works a t Niagara Fal ls , a t

Massena, a t Quebec and a t Sehawinigan Fal ls respect ively.(g) German y and Austria.

I t is real ly diff icult to give precise returns on the capacityfor prod uctio n of the se tw o cou ntrie s. I t has bee n give n asapproximate ly 10,000 tons , though i t i s not poss ib le ac tual lyto verify this figure.

In conclusion, th e fol lowing table of ac tua l world 's p rodu ctionmay be g iven, omit t ing a l l more or less hypothet ica l specula-t ions :

Uni ted S ta tes an d C ana da .F ra n ce . . . .Swi tzer landG r e a t B r i t a i nN orw ay . . . .I t a l yGerm any and Aus t r i a .

To t a l , a b o u t

. 70,000 to n s (?)

. 15,000

. 12,000 6,000 6,000

. 2,000

. 10,000 (?)

120,000 tons


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PA RT I I

P R O P E R T I E S O F A L U M I N I U M

C H A P T E R I

PHYSICAL PROPERTIES

Density : 2-6 (as annealed) , 2-7 (as worked, or when impuri t i( i ron and copper) are present) .

This p laces a lum in ium am on g the ligh tes t m eta l s ( lea11*4; nickel , 8-94; i ron, 7- 8; t in , 7 -3 ; z inc , 7 ; a n t imony, 6 ) .

Atomic Weight: 26-9.

Specific Heat: 0-22, increas ing w i th r i se of te m p er at u re . If inal ly reaches 0-308 at about the melt ing point .

Thermal Conductivity :36 ( s i lver=100) .Aluminium is a substance , therefore , having a great speci

hea t , and a h igh thermal conduc t iv i ty, which renders par t icular ly sui table for the manufacture of cooking utens i l

Electrical Conductivity and Resistance.


36/226


37/226

A N A LY S I S A N D G R A D I N G 17

quant i t i e s o f a lumina a re ve ry harmfu l on account o f i t si n fu s ib i l i t y a t c a s t i ng t empe ra tu r e s , * i t s h ighe r dens i t y, tand i t s inso lub i l i ty in the mol ten meta l .

T h i s i m p u r i t y m u s t t h e re f o re b e e s t i m a t e d . F u r t h e r m o r e ,a h ig h perc en tag e of a lu m in a seems to favo ur t h e fo rm at ion ofb low-ho le s . Fo r t he se r ea sons , t h e m e l t i ng u p of a lum in ium

scrap , more o r l e ss ox id i sed , g ives poor resu l t s .G R A D E S O F A L U M I N I U M .

A s a l r eady s t a t ed , t h e u sua l i ndu s t r i a l p r a c t i c e is t o e s t im a teon ly i r on and s i l i con , t he a lumin ium con t en t be ing de t e rminedb y difference this ob vi ou sl y giv es a f ictitious v al u e.

Grade I: A lum in ium no m ina l l y 99-5 % . i .e . t h e t o t a l am o u n tof i ron and s i l icon being equal to or less than 0-5 %.

Grade II: A lu m in ium no m ina l l y 99 -0 % . i .e . t he t o t a lamount o f i ron and s i l i con be ing equa l to o r l e ss than1-0 % .

Grade III: A l u m i n i u m n o m i n a l l y 9 8 - 9 9 % . i .e . t h e t o t a l

amount o f i ron and s i l i con be ing equa l to o r l e ss than 2 %.Though re ta in ing th i s long-es tab l i shed sys tem of c lass i f i ca -

t ion , the fo rego ing grad ing should be modi f ied , so as to t akeix>to account the impur i t i e s o f the second group as we l l a sthose of the f i rs t , s t i l l , however, ignor ing the a lumina.

W e the n hav e th e fo l low ing gra de s :%

Grade I: A lum in iu m co n ten t (by d iffe rence) 99-5 % or ove r.

Grade II: A l u m i n i u m 9 9 - 9 9 - 5 % .

Grade III: A l u m i n i u m 9 8 - 9 9 % .In the f i r s t two grades , the impur i t i e s o f the second group

(carb ides , su lph ides , copp er, z inc , t in , sod iu m, n i t ro ge n ,bo ron , an d t i t an iu m ) shou ld no t exceed 0 -3 % ; i n t he t h i r dgrade these impur i t i e s shou ld no t exceed 0-4 %, the i ron 1 %,and the s i l icon 0-6 %.

A lum ina is no t cons ide red i n ca l cu l a t ing t he pu r i t y , b u tsh ou ld n o t exceed 0-4 % for G ra d e I , 0 -6 % for Gr ad e I I ,a n d 0-8 % for G ra d e I I I Th ese are sa fe l imi t s to a l low


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39/226

M E C H A N I C A L P R O P E RT I E S 19of 10 mm. th ick sheet , and v a r i a t i o n of Scle roscope Hardnesswi th the a m o u n t of co ld work for shee t s of th e th in se r ies .

Discussion of r e su l t s .( i i) Variation of B r i n e l l H a r d n e s s and Shock Res i s t ance

wi th inc reas ing ann ea l ing t em pe ra tu r e , a ft e r va ry ing am ou nof cold work, using test pieces from sheets10 mm. th ick ( th ickseries).

Discussion of r e su l t s .

C. C U P P I N G VA L U E .D e p t h of impress ion and break ing load , us ing t es t p iecesof

meta l compr i s ingt he th in se r ies on ly.( i ) Variat ion of t h e s e p r o p e r t i e s w i t h a m o u n tof co ld work .(i i) Variation of these p roper t i es wi th inc reas ing annea l in

t empera tu re fo l l owing va ry ing amoun t sof co ld work .Discussion of r e su l t s .

D. F I N A L S U M M A RY.

E. C O N T E M P O R A RY L I T E R AT U R EON THE S U B J E C T .

A. T E N S I L E P R O P E RT I E S

Thin SeriesDimens ionsof tes t p ieces .

T Y P E I A . (Length 100 mm.Betw een shou lde rs j B r e a d t h 20 mm.( T h i c k n e s s 0-5 mm.

Area of cross sect ion 10 sq. mm.*Gauge leng th (f m e a s u r i n g e l o n g a t i o n )= \/66 61$


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20 ALUM INIUM AND ITS ALL OY S

I D . [Length 100 mm.Between shoulders\ Bread th 20 mm.

[Thickness 2 mm .Area of cross section 40 sq. mm.G a u g e l e n g t h = ^

Thick SeriesT Y P E I I . [Length 100 mm.

Betwe en shoulders J Bre adt h 15 m m .[Thickness 10 mm.

A rea of cross section 150 sq. m m .G a u g e l e n g t h = ^ 6 6 - 6 7 8 = 100 m m .

T E S T I N G L A B O R AT O R I E S .

The exper imen ts on th e var ia tion of mechanica l p rop er t i eswith cold work ( thin ser ies) and the cupping tes ts (both in theworked and annealed s ta tes) were carr ied out a t the " ChalaisM e u d o n " Lab ora tory. The exper im ents on the effect o fanneal ing at di fferent temperatures af ter cold work werecar r ied ou t a t the Conserva to i re des A r ts e t Met ie rs . R ep or t sof the la t ter, exper iments are given in the appendices .

I . Variation of the Tensile Properties (Tensile Strength, ElasticLimit, and Elongation) with the amount of cold work.

O F C O L D W O R K .

A m eta l , which, as th e resul t of work " i n t he co ld," i.e . a tre la t ive ly low tempera tures , has undergone permanent defor-m at io n , i s sa id to be "c o ld worked " or " work ha rd en ed ."The proper t ies of the meta l , thus t rea ted , a re changed , andthe amount of this change is a measure of the causetheso-cal led cold wo rk. A me tal which has been co m ple telyan ne al ed h a s, "by definit ion, zero co ld-work.

If S he the ini t ia l sect ion of a bar in the annealed s ta te andif s be the final section after cold work (drawing or roll ing),th e cold wo rk m ay be defined in term s of th e deform at ion asf o l l o w s :

Cold work__S(initial)s(final)~ i S S 3 x m

As has been poin ted out in th e auth or ' s work on " Coppe r


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M E C H A N IC A L P R O P E R T I E S 21

proper ti e s . Th e l a t t e r m ay ac tua l ly rem ain s t a t io na ry, whi lethe percentage of deformat ion cont inues to increase wi th thedeformat ion itself. We can therefore d is t inguish two values :

(a) Th e co ld work in t e r m s of de f orm at ion ( theore t i ca lcold work) .

(6) The cold work in terms of the change in mechanicalpropert ies (effect ive cold work).

In th is book, unless o therwise s ta ted , i t i s a lways the formerthat i s meant , and th is a l lows of easy evaluat ion in course ofm anufac tu r e .

(a) Thin Series

The tes ts on the th in ser ies were carr ied out on tes t p iecescut respect ively from sheets of the thicknesses specif ied :

T yp e l a . . Th ickne ss 0-5 m m .,, 16 . . 1-0 m m .,, I c . ,, 1*5 m m . Id . . 2-0 m m .

Sheets of each of the above th icknesses were subjec ted tothe fo llowing am ou nt s of cold work, and th e res ul ts inve s t iga ted .

Cold work 0 % R at i o S / sO (comple te ly annea led)5 0 % 1-5

1 0 0 % 2

3 0 0 % 4

Method of working sheets and slabs so as to obtain requiredamounts of cold work.

Two methods were employed in the p re l iminary work ingof the sheets and slabs.

F I R S T M E T H O D .

Annealed Metal. A s lab 40 m m . th ic k a t an in i t ia l tem pe ra-tu re of 450 is red uc ed to th e requ ired thic kn ess b y ho t rol l ing,wi thout in termedia te reheat ing , and is f ina l ly annealed a t350.


42/226

22 ALUM INIUM AND ITS AL LO YS

S E C O N D M E T H O D .A slab 40 mm. th ick, a t an in i t ia l temperature of 450, i s

reduced to a uniform thickness of 8 mm. by hot roll ing.Annealed Metal. The sheet , 8 m m . th ick , i s reduc ed to th e

requ ired th ickness by cold roll ing, wi th in term edi ate ann eal ingat 350 every 2 mm. reduction, and is f inally annealed at 350.

Cold-Worked Metal. Assuming that 100% cold work isdesired, the sheet , 8 mm . thick, is red uc ed by co ld roll ing ,wi th in terme diate anneal ing every 2 m m . redu ct ion , to dou bleth e f inal thickness required. I t is the n an ne ale d a t 350, an dcold rolled so as to reduce the section byone-half. A similarprocess is employed for the other degrees of cold work in-ves t iga ted .

A comparat ive s tudy of the cold working of th in sheetswas carr ied out by both these methods, whereas in the s tudyof the cold wo rking of thick sheets, an d in th e stu d y of an ne alin galone, th e second me thod only was em ploy ed. A l thou gh th esecond method is more uniform and more sound, i t has notgiv en resu lts superio r to those of th e first.

As will be seen below, it seems as if, up to a certain limit,

large amo un ts of cold work need no t be avo ided in m an ufa ctur e ,pro vid ed th at th is i s only an in term ediate s tag e, an d is fo llowedby a re-softening anneal .

A N A LY S I S

Thickness

I r o nSilicon

I r o nSilicon .A lumina .

I r o nSil iconAlumina .

I r o n

Cold work 0 %0-5 m m . 1 m m .

. 0-93. 0-56Cold

. 0-88

. 0-25

. 0-36

Cold. 0-81. 0-32. 0-24

Cold i0 88

% 0 - 8 2 %0-52

: work 50 %0-840-260-30

work 100 %0-830-380-29

work 300 %0 77

1-5 mm.

0-98 %0-56

0-970-390-26

0-700-230-26

0 85

2 m m .

0-95 %0-45

0-930-410-34

0-810-230-24

0 72

23


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M E C H A N I C A L P R O P E RT I E S 23

N U M B E R OF T E S T S .

For each degreeof co ld work , two sheets were usedfor thetens i le tes ts , and in each sheet three tes t p ieces werecutlongi tudinal ly and th ree t r ansverse ly.

THIN SERIES(Sheet 1 mm. th i ck)

5 0 TOO 15 0 200

Cold Work'2 5 0 300%

F I G . 4 V a r i a t i o n i n M e c h a n i c a l ( t e n s i l e ) P r o p e r t i e s w i t hC o l d " Wo r k .

R E S U L T S O F T E S T S .

2 4 A L U M I N I U M A N D I T S A L L O Y S


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direct ion, longi tudinal or t ransverse , in which the tes t p ieceswere cu t .

Cold work 0 % (annea led s ta te ) :Elastic Limit: 4-5 kg. per sq. mm. (2-86 tons per sq. in.) .Tensile Strength : 9-0 kg. per sq. m m . (5-72 to ns p er s q. in.) .Elongation : 40 %.

Cold wo rk 50 % :

Elastic Limit: 12-0 kg. per sq. mm. (7*62 tons per sq. in.).Tensile Strength : 14*0 kg . per sq. m m . (9-09 to n s pe r sq . in.)Elongation: 11 %.

Cold work 100 % :Elastic Limit: 14-0 kg . per sq. m m . (8-89 ton s per sq. in.) .Tensile Strength : 15-0 kg . per sq. m m . (9-52 to ns p er sq . in.)Elongation : 9 % .

Cold work 300 % :Elastic Limit: 17-5 kg . per sq. m m . (11-11 to ns pe r sq . in. ) .Tensile Strength: 18-0 kg. per sq. m m . (11 -43 to n s p er sq. in.).Elongation: 6 % .

(i) Merely cold working to the extent of 50 % has completelychan ged th e p rop er t i es of a lumin ium, and t he E long a t ion hasbeen red uce d to a qu ar te r of i t s or ig inal valu e . Con sequent ly,i f work hardening is undesi rable , even a very smal l amount ofdeformat ion must be avoided, s ince the changes in theproper t i es t ake p lace very marked ly f rom the ou t se t .

(ii) Th e ma xi m um co ld work , beyond which de te r io ra t ionan d dis in teg rat io n m a y se t in , i s reached when the Tensi leS t r en g th is app rox im a te ly doub led .

( i i i ) If cold work be expressed, no longer in terms of thedefo rm at ion , b u t in ter m s of the changes in th e prop er t ies , the n,choosing as var iable the Tensi le St rength , and employing thefo rmu la

Co ld w o r k = whe re R= Te ns i l e S t r eng thr (cold worked)

r=Tens i l e S t r eng th(annealed)

we have, in the case of the thin series, the following results :Cold w ork (de form atio n) 0 % Cold work (effective) 0

/ioo %

M E C H A N IC A L P R O P E RT I E S 25


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I t seems, therefore , th a t 200-300 % cold wo rk i s th e m a x im u mfor the working of a luminium, g iv ing what might be ca l led the" M aximu m Effec t ive C old W or k. "

L O X U E N C E O E T H I C K N E S S ( T H I N S E R I E S ) .

The var ia t ion in th ickness be tween 0-5 mm. and 2-0 mm.exerts only a s l ight effect on the resul ts , so that the meancurve given for tes t pieces of 1-mm. th ick ne ss m a y be ta k enas the curve for al l the thin ser ies .E F E E C T O N T E N S I L E P R O P E RT I E S O E T H E D I R E C T I O N I N W H I C H

TEST PIECES WERE CUT.The E lon ga t ion in the t r ansve r se t e s t p ieces i s l es s t h a n th a t

in the longi tudina l .Cold w ork 0 % Difference 10 %Cold w ork 50 % an d abo ve M ax im um di fference 40%

In the Tens i l e S t reng th and E las t i c L imi t the re i s p rac t i ca l lyno difference.

(b) Thick SeriesTh e tes ts on th e " Thick Series " h av e been ca r r ied ou t on

tes t p ieces of Typ e I I , th ickness 10 m m . , cu t f rom she ets ofth is th ickness .

Th e following different am ou nts of cold w or k were in ve st i -gated :

Cold w ork 0 % R at io : I n i t i f S e c t i o n ^ Q ( l e t e lF i n a l S e c ti o n a n n e a l e d )

5 0 % 1.5

1 0 0 % 2 3 0 0 % 4

A N A LY S I S .

Cold work 0 % :A lu m in iu m . . . . 99-00 %Ir o n 0-64 %Sili con . . . . 0-33 %C arb on . . . . 0-03 %A lu m in a . . . . t r a c e s .

Cold work 50 % :A lu m in iu m . . . . 98-80 %


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Cold work100 % :A l u m i n i u mIron .SiliconCarbonA l u m i n a

98-60 %0-84 %0-41 %0-07 %

t races .

THICK SERIES(Longitudinal)

11

10

5 0 2 5 05 o T$o 2 o c T

C o fd W o r k

F I Q 5 Va r i a t i o n i n M e c h a n i c a l P r o p e r t i e s w i t h C o l d W o r k


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Elongation. M in imum , 8 % . M ax imum , 38 % .In" the case of a lu m ini um in th i n shee ts as com pared w i ththick,

(i) The co ld wo rk , w ha tev er i t s am ou nt , is more hom ogeneousth roughou t t he th i ckness .

(i i) The effect of annealing is more complete.

THIN SERIES(Test Pieces 0.5 mm. thick)

1 0 0200 300 400

Temperature5 0 0

F I G . 7 . V a r i a t i o n i n M e c h a n i c a l P r o p e r t i e s o n A n n e a l i n g a td i f f e r e n t T e m p e r a t u r e s a f t e r 5 0 % C o l d W o r k .

F I G . 6 . T E S T S O K T B A N S Y E R S E T E S T P I E C E S .



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I I . Variation of Tensile P roperties with increasing Annealing;Temperature following varying amoun ts of Gold Work.

(a) Thin Series

EXPEEIMEKTAL DETAILS OP THE TESTS.The tes ts were carr ied out on two ser ies of tensi le tes t p ieces

f rom shee ts of a lum inium , th e on e 0-5 m m . th ic k , Ty pe la ,

THIN SERIES(Test Pieces 0'5mm. thick)

TOO 200 300 400T e m p e r a t u r e

5 0 0 6 0 0 C

F I G . 8 . V a r i a t i o n i n M e c h a n i c a l P r o p e r t i e s o n A n n e a l i n ga t d i f fe r e n t Te m p e r a t u r e s a f t e r 1 0 0 % C o l d W o r k .

30 A L U M I N IU M A M ) I T S A L L O Y S


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30 A L U M I N IU M A M ) I T S A L L O Y S

I N V E S T I G AT I O N O F T H E D U R AT I O N O F T I M E N E C E S S A B Y F O BC O M P L E T E A N N E A L AT VAB IO TJS T E M P E B A T U B E S .

Prel iminary tes ts have been carr ied out wi th a view todeterm ining th e minim um t im e necessary to give th e p roper t iescharacter is ing each temperature .*

40

35

3 0

2 5

ton

3 2 0LJ

15

10

5

0

Kg.per

16

14

12

10

8

6

4

0

THIN(Test

\ \\ >\\

\v\\

V\\\

SERIESPieces OSmm.thick)

% Elongation

\ / ^ S v ^

\

\ | \ ^ Tensile \\

Strength

\\ \

I\/ \N ^ ^ Elastic.J ~"Umii~

/

11

1 0

100 5 0 0 60 0 C00 300 400Temperature

FIG. 9.Variation in Mechanical Properties on Annealingat different Tem peratu res after 3 00 % Cold Wo rk.



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T E S T P I E C E S 0-5 m m . T H I C K . T Y P E 1 A .Tigs . 7 , 8, an d 9 sum m ar i se the resu l t s o b ta in ed .

S TA GE S O P A N N E A L I N G .

Whatever the amount of work, the fo l lowing s tages can bed i s t ingu i shed :

(i) Region of cold work,(ii) Region of softening,

( i i i ) Region of complete anneal ,(iv) R eg ion of f alling-off of E lo n ga tio n .

THIN SERIES(Test pieces 2mm.thick)

100 5 0 0 6 0 0 C00 300 400Temperature



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as gi ve n in Fig , 4 . T h e effect of te m pe ra tu re s up to 150 istherefore ins igni f icant .

(ii) Region of Softening ;150-350 .Th i s i s a t r ans i t i on s t age , i n wh ich the a lumin ium becomes

sof te r, and gradual ly acqui res the proper t ies of comple te lya n n e a l e d m e t a l .

THIN SERIES

(Test Pieces 2mm. thick)

100 200 300 400

Temperature500

- 1 1

1 0

F I G . 1 1 . V a r i a t i o n i n M e c h a n i c a l P r o p e r t i e s o n A n n e a l i n g

a f t e r 1 0 0 % C o l d W o r k .

( i i i ) R e g i o n of Complete A n n e a l ; 3 5 0 - 4 5 0 .

T h i s i s t h e r e g i o n i n w h i c h t h e e x t e n t o f a n n e a l r e m a i n s

a p p r o x i m a t e l y c o n s t a n t ; t h a t i s t o s a y , i n w h i c h t h e p r o p e r t i e s

o f t h e m e t a l a r e a l m o s t t h e s a m e a f t e r a n n e a l i n g a t a n y t e m p e r a -

t u r e w i t h i n t h i s r a n g e

M E C H A N I C A L P R O P E RT I E S


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350 t o 450 i s , there fore , th e op t im um ann ea l ing rang e of

t e m p e r a t u r e .(iv) Region of Falling-off of Elongation ;450-500 .

In th i s reg ion there i s a decrease in the Elonga t ion , wi thoutany app rec i ab l e change in t he Tens i l e S t r eng th and E la s t i cL i m i t .

I 8 Kg permm 2

THIN SERIES(Test Pieces 2mm.thick)

100 200 300 400 500 600CTemperature

F I G . 12.Variat ion in Mechanical Propert ies on Annealingafter 300 % Cold W ork.

N O T E S O N T H E R E S U L T S .

( i) T h e s o f t e n i n g i s t h e m o r e a b r u p t a s t h e o r i g i n a l c o l dw o r k i n c r e a s e s .


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The results are as follows :

BathOil .Sodium nit rite .Potassium nitrate

Temperature100-125-150-175-200-225-250275-300-325-350-375-400-425-450475-500-525-550-575-600

Duration ofTime

6 minutes.42

Tigs . 13 and 14 summarise the variat ions in mechanicalpropert ies for the thick series (sheets 10 mm. thick).

THICK SERIES

4 0

35

O 3 0

a"00

c 2 5UJ

2 0

10

0ur

K gperm m 2

Elongation

ElasticLimit

10

9

8

7

6

5 Q.tnc

3

2

1 0 0 200 300 400Tempera ture

5 00 600C

F I G . 1 3 . Va r i a t i o n i n M e c h a n i c a l P r o p e r t i e s o n A n n e a l i n ga f t e r 1 0 0 % C o l d Wo r k .

F I G S . 1 3 ( 1 0 0 % C O L D W O R K ) A N D 1 4 ( 3 0 0 % C O L D W O R K ) .



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B . H A B D N E S S A ND S H O C K R E S I S TA N C E

I . Variation of the Brinell Hardness and Shock Resistance withthe amount of cold work, using test pieces taken fromsheets 10 mm . thick, and of the Shore scleroscope hardness,with the amount of cold work, for sheets of the thin series.

H A R D N E S S T E S T S .

(a) Brinell Tests on thick sheets.These were carr ied out under a load of 500 kg. and 1000 kg.

respec t ively, us in g a ba l l 10 m m . in dia m ete r. Th e resul ts areshown in Fig . 15.

THICK SERIES(Test Pieces 10mm. thick)



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As is evident f rom a compar ison of Fig . 15 and Fig . 5 , thecurves o f Tens i l e S t reng th and E las t i c L imi t p lo t t ed aga ins tcold work are of the same genera l form as the hardness curves

42

41

40

39

38

37

36

3

g34

3 3;

I3 1

| 30

29

28

27

26

25

24

23

22

21

THICK SERIES

Brine//

ShockResistanc

5 0 1 00 150 20OCold Work

2 5 0 300%

F I G . 1 5 . Va r i a t i o n i n M e c h a n i c a l P r o p e r t i e s ( H a r d n e s sa n d S h o c k ) w i t h C o ld W o r k


A l d l i i B i l l H d f 23


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Annealed a luminium possesses a Br inel l Hardness of 23under 500 or 1000 kg. , corresponding wi th a Tensi le St rengthof app rox im atel y 10 kg . per sq . m m . (6-35 ton s per sq . in . ) .In t he case of th e th ick ser ies, th e ma xi m um hard nes s , as alsothe maximum Tens i l e S t reng th , occurs a t 200 % co ld work .

(b) Shore Scleroscope T ests on thin sheets.

As bal l tes ts are impossible on th in sheet , rebound tes tswere made , us ing the Shore appara tus , on shee t s o f the th inseries, possessing r esp ecti vel y 50 % , 100 % , a nd 300 % coldwork .

Th e average sc leroscope num bers of sheets 1 an d 2 m m . th ickare as follows :

Average scleroscope numberTest pieces 1 mm. thick 2 mm. thick

A s an ne al ed . . 4-5 5-55 0 % co ld w or k . 16-0 11-5100 % co ld w or k . 24-0 14-0300 % col d w or k . 28-0 16-0

The sc le roscope num be rs va ry wi th the th ickness , b u t ,w ha tev er th e th ick nes s , th e scleroscope num ber of comple te ly

anne a led m eta l va r ies be tween 4 an d 6, p rov id ing , the re fore ,a convenient means of ver i fy ing the extent of anneal .

S H O C K T E S T S .

These were ca r r i ed ou t on t es t ba rs , 55x 10X10 mm. , wi tha Me snager n ot ch of 2 m m . de pth , us ing a 30 kg. m . ch arp ypendulum of the Conserva to i re des Ar t s e t Met ie r s .

Th e resul ts ar e a lso show n in Fig . 15. I f th e Shock Resis ta ncecurv es ( longi tudin al an d t ransverse) of Fig . 15 be co m paredw ith th e Elo ng at i on cu rves of Figs . 5 an d 6 , i t wi ll be seen t h a tth ey a re of iden t ica l sh ape .

At 50 % cold work, the Shock Resis tance reaches a lmost i t sm in im um va lu e . In th e annea led s ta te , the Shock Res i s tancevar i es bet w een 8 an d 8-5 ki logram m e-metres per sq . cm . ,w i th ou t an y a pp rec iab le d i fference betw een tes t p ieces cu tlon gi tu din al ly or t ran sve rsel y. This d i fference, how ever,becom es m ore ma rk ed as the co ld work inc reases .

M in im um S hock R es i s ta nce , 300 % co ld work ( long itud ina l)5 kg . m. pe r sq . cm.



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I I . Variation of Brinell Hardness and Shock Resistance with

increasing annealing temperature after varying amounts

of cold work, using test pieces taken from sheets 1 0 mm,

thick.

F i g s . 1 6 a n d 1 7 , c o r r e s p o n d i n g w i t h 1 0 0 % a n d 3 0 0 % c o l d

w o r k r e s p e c t i v e l y , s u m m a r i s e t h e r e s u l t s .

THICK SERIES(Test Pieces 10mm. thick)

3 7

100 200 300 400Temperature 5 0 06 0 0 C

F I G . 1 6 . Va r i a t i o n i n M e c h a n i c a l P r o p e r t i e s ( H a r d n e s s a n dS h o c k ) o n A n n e a l i n g a ft e r 1 0 0 % C o l d W o r k .

H A K D N E S S .

T h e h a r d n e s s c u r v e s u n d e r 1 0 0 0 k g a n d 5 0 0 k g a r e s h o w n


these curves i s not so much to compare the ac tua l hardness


60/226

these curves i s no t so much to compare the ac tua l hardnessnu m be rs un de r 500 an d 1000 kg . , as to gain some indica t ionof th e t re nd of these value s un de r tw o different loads. T head va nta ge of th i s i s ev id en t ; for ins ta nc e , in th e case of h ightem pera tu re t e s t s , whe re t he d e t e rm ina t io n of ha rdness und e r

40

39

38

37

36

35

34

S3

3

| 31

| 3 0

I 2 8

27

26

25

24

23

22

2120 1

1000 Kg

THICK SERIES(Test Pieces 1 Omm. thick)

ShockResistanceKg.mp e r

ShockResistance

10

98

7

[6

54

100 5 0 0 6 0 0 C00 300 " 40 0T e m p e r a t u r e

FIG. 17.Variation in Mechanical Properties (Hardness andShock) on An nealing after 300 % Cold Work.

1 0 0 0 k g . w o u l d n o t b e p o s s i b l e , t h e h a r d n e s s m u s t b e d e t e r m i n e du n d e r 5 0 0 k g . S i n c e w e h a v e a l l t h e n e c e s s a r y d a t a , w e m a y t h e ne x t e n d o u r r e s u l t s a n d m a k e s u c h d e d u c t i o n s a s a r e u s e f u l


S H O C K R E S I S TA N C E


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S H O C K R E S I S TA N C E .

I t should be observ ed th a t in the co ld-work reg ion (0-150 c.)t h e S h o c k R e s i s t a n c e r e m a i n s a p p r o x i m a t e l y c o n s t a n t , h a v i n ga va lu e of ab o u t 4 kg . m . pe r sq . cm . for 300 % cold w ork .I t r i ses gradua l ly in the sof ten ing reg ion , and in the comple te lyan ne a le d zone i t reaches 8 kg . m . pe r sq . cm . on anne a l in g a t400 c . af ter 100 an d 300 % cold w ork . I t con t inu es to inc reas eslowly up to 9 kg .m . pe r sq . cm . on an ne al i ng at 600 af ter 100 %cold wo rk , a n d ev en to 10 kg . m . per sq . cm . on an ne a l in g a t th i st em pe ra t u r e a f te r 300 % co ld work .

C. CtrpprsrG T E S T S

Depth of Impression and Breaking Load

E X P E R I M E N TA L D E TA I L S .

Cupping tes t s were car r ied ou t on shee t meta l by means ofth e Pe r soz ap pa ra t us (F ig . 18) i n t h e Cha la i s l abo ra to ry .

Th i s appa ra tus cons i s t s , e s sen t i a l l y, o f a g radua ted rodfurn ished a t one end wi th a p la te and a t the o ther wi th a ba l l20 m m . in d iam ete r. Th is ba l l res t s on a c i rc le 90 m m . ind ia m e te r t ak en from th e shee t t o be t e s t ed an d g r ipped be twee ntw o se r r a t e d an nu la r r i ngs of 50 m m . in t e rna l d i am e te r.

By sub jec t ing the who le appa ra tus t o a compres s iona l s t r e s sbe tw een th e two p l a t e s of a t e s t i ng mach ine , s tead i ly i nc reas ingpre ssu res can be appl ied to th e cen t re of th e c i rc le , th ro ug h t h eba l l . Th is com press ion i s con t inue d r ig h t up to the po in t ofrup tu re o f t he dome wh ich fo rms , i n t he shee t , unde r t he

pressure of the ba l l .The b reak ing load , and the dep th o f t he impres s ion madein th e shee t , a t t h e po in t o f rup tu r e , ca n th u s be me asu red .The appa ra tus pe rmi t s t he measu remen t o f t he dep th o fimp ress ion w i th a m ax im um er ror of -02 to -03 m m .

I . Variation of Depth of Im pression and Breaking Load withthe amount of Gold Work.

F i g s . 19 an d 20 sum ma r i se t h e r e su l t s . Th e va lues d epen dup on tw o var iab les :

(i) The percentage of cold work,( i i ) The thickness of the sheets


I


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I


c a r r i e d o u t w e r e t h o s e c o m p r i s i n g t h e t h i n s e r i e s ; 0 -5 m m


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c a r r i e d o u t , w e r e t h o s e c o m p r i s i n g t h e t h i n s e r i e s ; 0 -5 m m . ,1-0 m m . , 1-5 m m . , a n d 2 -0 m m . i n t h i c k n e s s r e s p e c t i v e l y.

F i g . 1 9 s h o w s f o r e a c h t h i c k n e s s t h e v a r i a t i o n of t h e D e p t hof I m p r e s s i o n a n d B r e a k i n g L o a d w i t h c o l d w o r k .

THIN SERIES

16

15-

14

13

12

E nEc 1 0

o* 9tn

a. S

*oX-MQ.

Q5

1000B r e a k i n g

L o a d Load (2 mmj

Qepth\ X ^-^^ /)ep^// o / Impression\ \l '0 m/nT's, "* (o

Loadfl mm.)

lnad(0'5

50 100 150 200Cold Work

250 300%

F I G . 1 9 . C u p p i n g Te s t s : Va r i a t i o n i n ' B r e a k i n g L o a d a n dD e p t h of I m p r e s s i o n w i t h C o l d W o r k . T e s t p i e c e s oft h i c k n e s s s p e c if i e d ( 2 - 0 , 1 -5 , 1 -0 , a n d 0 - 5 m m . ) .

ALUMINIUM AND ITS ALLOYS


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T h e a b s o l u t e m i n i m u m c o l d w o r k s h o u l d b e s p e c i f i e d f o r s h e e ta l u m i n i u m r e q u i r e d f o r p r e s s i n g o r o t h e r w o r k o f a s i m i l a r

n a t u r e . T h e a m o u n t o f c u p p i n g , w h i c h a n n e a l e d s h e e t w i l l

s t a n d , i s c l e a r l y s u p e r i o r t o t h a t w h i c h s h e e t , w o r k e d e v e n

v e r y l i t t l e , c a n s u p p o r t .

1000 Kg. T H 1 N S E R I E S

B r e a k i n g

300%WO% Cold'50 % Work0 %

0*5 10 1*5

Thickness of Sheet2*0mm.

F I G . 2 0 . C u p p i n g Te s t s : Va r i a t i o n i n B r e a k i n g L o a d a n d D e p t h ofI m p r e s s i o n w i t h t h i c k n e s s , a t s p e c i f i e d a m o u n t s of C o l d Wo r k(0 , 50, 10 0 an d 300 %) .

P i g . 2 0 , w h i c h i s d e r i v e d f r o m T i g . 1 9 , s h o w s t h e v a r i a t i o n o f

B r e a k i n g L o a d a n d D e p t h o f I m p r e s s i o n w i t h t h i c k n e s s i n t h e

c a s e o f t e s t p i e c e s h a v i n g b e e n s u b j e c t e d t o 0 % , 5 0 % , 1 0 0 % ,

a n d 3 0 0 % c o l d w o r k r e s p e c t i v e l y .

I t s h o w s t h a t a n i n c r e a s e o f t h i c k n e s s m u s t b e r e s o r t e d t o ,

i f a n i n c r e a s e d c u p p i n g v a l u e i s d e s i r e d .

C O N C L U S I O N . W h a t e v e r t h e t h i c k n e s s , a l l s h e e t d e s t i n e d f o r

p r e s s i n g s h o u l d b e a n n e a l e d a n d t h i s c o n d i t i o n s h o u l d b e


w orked to 50 % , 100 % a n d 300 % . Fi gs . 21 , 22, an d 23


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, g , ,summar i se the r e su l t s ob ta ined on Typela (0-5 mm. th ick) .T h e y s ho w t h a t t h e m a x i m u m v a l u es of t h e D e p t h of I m p r e s -s ion an d Brea k ing L oa d a re r eached in th e r eg ion 375O-425O,and these va lues r emain approx imate ly cons tan t up to 600 .

THIN SERIES(Test Pieces 0'5mm. thick) .

1514

13

12

E 1 1

o

2Q.

JC 6

fao

BreakingLoadKg

2 1 0

200 j

1 9 0

180

J170 /

160 /

Uepth of

^*mJ 0' Impression

/ Load

1 0 0 5 0 0 600C00 300 400Temperature

F I G . 21.Chipping Tes ts : Var ia t ionin B r e a k i n g L o a d a n d D e p t hof Imp res s ion on Anneal ing a f te r 50 % C old W ork .

T h e y s h o w , f u r t h e r , t h a t t h e final r e s u l t s ( D e p t h o f I m p r e s s i o n

a n d B r e a k i n g L o a d ) a r e h i g h e r a s t h e i n i t i a l c o l d w o r k i sg r e a t e r .

T h e f o l l o w i n g t a b l e s u m m a r i s e s t h e r e s u l t s :

S H E E T S 0 -5 m m . T H I C K

46 ALUMINIUM AND ITS ALLOTS

F i g s 24: 25 an d 26 g i v e t h e r e s u l t s f o r T y p e Id ( 2- 0 m m


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F i g s . 24:, 25 , an d 26 g i v e t h e r e s u l t s f o r T y p e Id ( 2 0 m m .t h i c k ) . T h e y s h o w t h a t f o r s h e e t 2 -0 m m . t h i c k , a s i n t h ec a s e of s h e e t 0 -5 m m . t h i c k , t h e D e p t h of I m p r e s s i o n a n dB r e a k i n g L o a d r e a c h t h e i r m a x i m u m v a l u e s i n a p p r o x i m a t e l yt h e s a m e t e m p e r a t u r e r a n g e , b u t s l i g h t l y e x t e n d e d (3 rJ5-4:50o)y

THIN SERIES

14

13

12

o

*S5 90)

I8

a.Q

BreakingLoad

K g

2 0 0

190 ^S

180 V

170 > ^

160

1500 100 200

Depth ofj f Impress ion

/r v**^" Breaking

S Load

/

300 400 560 60Temperature

FIG. 22.Cupping Tes t s : Var ia t ion in Breaking Load andD e p t h of Impression on Annealing after 100 % Cold Work.

a n d t h e s e v a l u e s r e m a i n a p p r o x i m a t e l y c o n s t a n t u p t o 6 0 0 .T h e s a m e r e m a r k s a s b e f o r e a p p l y a s t o t h e r e l a t i o n b e t w e e nt h e i n i t i a l c o l d w o r k a n d t h e final v a l u e s ( B r e a k i n g L o a d a n dD e p t h of I m p r e s s i o n a t r u p t u r e ) . T h e f o l l o w i n g t a b l e m a yt h e r e f o r e b e d r a w n u p :

M E C H A N I C A L P E O P E RT I E S 47


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D . F I N A L S U M M A R Y

I n t h i s c h a p t e r t h e f o l l o w i n g p r o p e r t i e s h a v e b e e n c o n -s i d e r e d :

(a ) T e n s i l e p r o p e r t i e s .(&) H a r d n e s s a n d S h o c k R e s i s t a n c e .(c ) C u p p i n g p r o p e r t i e s .

THIN SERIES15 B re a k in g (Test Pieces O'Smm. thick)

14

13

12

Q

Load

Depth of

Impression

BreakingLoad

150 ,100 200 300 400

Temperature500 600C

FIG. 23.Cupping Tests : Variat ion in Breaking Load andD e p t h of Impression on Annealing after 300 % Cold Work.

T h e w o r k h a s b e e n c a r r i e d o u t f r o m a t w o f o l d s t a n d p o i n t

48 A L U M I N I U M AND ITS A L L O Y S

(i) COLD WORK.


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This ma y be cons idered under two headings:

(a ) The i n t e rmed ia t e co ld -worked s t a t e du r ing manufacture, whose effectis r emoved by a final anneal.

(b) Th e f inal cold-worked s tate of the m a n u f a c t u r e dp r o d u c t .

THIN SERIES(Test Pieces 2mm thick)Depth of

Kg

15

14

13

12

I"o 1 0'55

I

I *

S

IQ 5

1000BreakingLoad

9 5 0

Impression

9 0 0

8 5 0

8 0 0

Breaking

Load

700

100 200 300 400

Temperature50 0 6 0 0 C

F I G . 2 4 . C u p p i n g T e s t s : Va r i a ti o n i n B r e a k i n g L o a d a n dD e p t h of I m p r e s s i o n o n A n n e a l i n g a f t e r 6 0 % C o l d Wo r k .

( a ) Intermediate Cold Work.

T h e u t i l i s a t i o n o f l a r g e a m o u n t s o f c o l d w o r k , 2 0 0 a n d 3 0 0 % ,

M E C H A N I C A L P R O P E RT I E S

(b) Final Cold Work,


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Cold work is far f rom adv isab le , pa r t i cu la r lyin ae ronau t i c a lwork. I t hard ly seemst o cons t i tu te a s tab le s t a te , and shou ldespecia lly be avo ided in m ater ia l subjec ted to con sta nt v ib ra t io n .

W e are therefore of th e opin ion tha t a lumin ium shou ldb eused in the annea led cond i t ion , ce r t a in lyas regards ae ro-nau t i c a l work ; t h e increased s t rength , which resul ts f rom

cold work, as descr ibed in th is chapter, should be a t t a i n e dby other means , suchas increase of th ickness , or th e emp loy -m e n t of al loys.

THIN SERIES(Test Pieces 2mm. thi ck)

16

15

14

13

12

Ec 10o

'5 >

oa. 8Z. 7

o-c 6a.


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M E C H A N IC A L P R O P E R T I E S 5


71/226

E . C O N T E M P O R A RY L I T E R A T U R E D E A L I N G W I T H T H E S U B J EO F T H E M E C H A N I C A L P R O P E R T I E S A F T E R C O L D W O RA N D A N N E A L I N G .

As rega rds th e va r ia t io n in m ech anica l p ro per t ies w i th co

work and annea l ing , a luminium has been subjec ted to vede ta i led inves t iga t ion by Rober t Anderson ,* who has publ i shthe following articles :

(1) Er i chsen Tes t s on Shee t A lum in ium ( " I r o n A ge11th Ap ri l , 1918, p p . 950 an d 951).

(2) A nne al ing a n d R ecr ysta l l i sa t ion of Cold-Rol led Am inium Shee t ( " M eta l lu rg ica l an d Chem ica l E ng inee r ingVol . X V I I I , No . 10 , p p . 525-7 , 15 th M ay, 1918).

(3) Te sts on Sh eet A lum ini um . Soften ing of Co ld-Ro llShee t b y he at i ng for an ex tre m ely sho r t t im e a t d iffere

tem pe ra tu res . B e t te r Pro per t ies for D raw ing . Effec t of Ovannea l ing ( " I r o n A ge , " 18 th Ju ly , 1918).

For the comple te repor t we mus t re fe r the reader to tor iginal papers deal ing wi th these most in teres t ing invest igt ions , of which we can only g ive an abr idge d su m m ar y. W

m ay say , a t once, th a t , w here com parison is poss ible , th er e is con t rad ic t ion be twee n A nde rson ' s resu l t s an d our own, as g ivin th is ch ap ter. C er ta in ex pe r im en tal m eth od s are differen

A N D E R S O N ' S D E F I N I T I O N O F M A X I M U M S O F T E N I N G O R A N N E A

The maximum sof tening is def ined in terms of the Shosc le roscope num ber. Th e m eta l m ay be rega rded as com ple tannealed when the sc leroscope hardness is 4-5 , th is being tmaximum sof tness f rom the point of v iew of pract ical ro lh" Sheets having th is degree of hardness ," says Anderson, "

f t i l th gh i l l i h

5 2 A L U M I N I U M A N DIT S A L L O Y S

In h i s paper on "Annea l ing and Becrys ta l l i sa t ion o f Co ld -R l l d A l i i S h t " t h t h t i l l


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R o l l e d A l u m i n i u m S h e e t , " t h e a u t h o r p r op o s es p a r t ic u l a r lyt o sh ow t h e inf luence of th e du ra t io n of a n ann eal a t d i fferentt e m p e r a t u r e s o n t h e p r o d u c t i o n of m e t a l s u i t a b le for d r a w i n ga n d p r e s s i n g u n d e r t h e b e s t c o n d i t i o n s .

T h e p e r c e n t a g e r e d u c t i o n of a r e a i s d e t e r m i n e d . T h e S h o res c l e r o s c o p e n u m b e r s h o w s t h e h a r d n e s s a n d h en c e t h e d e gr ee

of so f tnes s . T h e Er ichs en ma ch i ne * shows the su i t ab i l i ty ofth e m e ta l fo r fu r th e r w ork , no t on ly by the dep th of the dom e ,b u t by t h e l a rg e o r sm a l l app ea ra nce of the g ra ins . Th ean ne a l s we re ca r r i e d ou t in a l abo ra to ry e l ec t ri c fu rnace , t em -p e r a t u r e s b e i n g m e a s u r e d t o t h e n e a r e s t 5 C , a n d t h e t i m e sb e i n g r e c o r d e d .

P A P E R O P 1 5 T H M A Y , 19 18 ( " M E TA L L U R G I C A L A N D C H E M I CA LE N G I N E E R I N G " ) . I N F L U E N C E o r T EM P ER ATU R E A N DDURATION OF ANNEAL.

Anneal ing cold- ro l led a luminium sheet of d i fferent th ick-ne ss es for tw en ty -fo ur ho ur s a t 370 gav e , for a Shore sc lero-s c o p e n u m b e r b e t w e e n 4 a n d 5, E r i c h s e n d o m e s s h ow i n g g ro s sc r y s t a l l i s a t i o n , a n d m e t a l l i t t l e s u i t a b l e f o r d r a w i n g .

Sys temat i c t e s t s were ca r r i ed ou t on shee t o f th i ckness andp e r c e n t a g e r e d u c t i o n o f a r e a g i v e n i n t h e f o l l o w i n g t a b l e :

No.1

23456789

10

Thicknessmm. inches2-58

2-051-701 321090-790-680-540-400-30

1087

-0841-0650-0512-040103210275022001690128

% Reductionof Area

54-85

63-3071-6077-6082-60868890-5092-7094-50

Gaugef10

121416182022242628

M I N I M U M T E M P E R A T U R E N E C E S S A RY F O R O B TA IN IN G A SC L E R O -S C O P E N U M B E R O F 4 - 5 .

At a temperature of300. I n th e case of she ets 1 to 5 ( inclusive),60 m in u te s w i l l h ar d ly suffice to g ive a sc leroscope num ber

M E C H A N I C A L P K O P E RT I E S 53


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At 350. 30 m in u te s ar e suff icient for sh ee t 1.20 m in u te s are suff icient for sh ee ts 2 a n d 3 .15 m in u te s are sufficient for sh ee ts 4 to 10 (inclus ive

At 400. 10 m in u te s ar e sufficient for al l sh ee ts .

At 600. 10 m in u te s ar e sufficient for rea ch ing a sclerosconumber ve ry nea r the lower l imi t .

Anderson ' s exper iments , in agreement wi th ours , show thannealing has a more rapid effect , the greater the ini t ial cow ork. T he y fur ther show th a t , f rom t h e po in t of v iew

working and of fineness of grain, i t is necessary to investigate tgreates t depth of impress ion given af ter an anneal of thshor tes t poss ible durat ion, and a t the lowest poss ible tempertu re , con sistent w ith a scleroscope har dn es s of 4- 5 an d smo oth Er ichsen dom e. A nderson has th u s es tab l i shed thfol lowing curve (Fig. 27) which, for the condit ions just s tate

1 O

ErichsenNumber

1 1

10(Depth .oflmpression)Q

(mm.) *87

/

0-5 V 0 1-5 2*0 2*5 m m.Thickness

FIG. 27.Variation in Depth of Impression with Thickness.A l d Al i i Sh


Anderson ' s work shows tha t p ro longed annea l ing i s ve ry

harmfu l and a l so tha t no t on ly mus t the tempera tu re becareful ly se lec ted but a lso the minimum time required at th is

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Aluminum - Aluminium and Its Alloys

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