Fundamentals of welding.pptx

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Fundamentals of Welding

D.SELVAKUMARAN

Course DirectorAW!"



Types of metal joining

• Ri#eted $oints

• %olted $oints

•

Welded $oints



RIVETED JOINTS



BOLTED JOINTS



Welded joint



Welded joint



m tat ons o r veteand

olted joints• Load &earing

• Di'cult for (ig(er t(ic)ness

•

%olts can &e unscre*ed• Ri#ets and &olts are +rotruding

• Fillet $oints, &utt $oints cur#ed $oints,

are di'cult. Additional -anges arenecessar

t t t



m tat ons o r veteand

olted joints• Ri#ets and &olts are +rotruding

• Fillet $oints, &utt $oints cur#ed $oints,are di'cult. Additional -anges arenecessar



!dvantages of "elding

• /ermanent $oint

• Wit(stands (ig( +ressure or force or load

• 0ccu+ies less s+ace

• 1as less *eig(t

• Wit(stands (ig( tem+erature

• 2uic) +rocess

• An +ro3le can &e *elded. Di4erent $ointt+es i.e. %utt, 3llet, la+, corner $oint+ossi&le



%asic 5oint !+es

&utt

teela+

corneredge



A++lica&le Welds for %utt $oint

S6uare 7roo#e*eld

Single V *eld

Single U*eld

Single %e#el *eld

Single 5 *eld



A++lica&le Welds for %utt $oint

Dou&le V *eld

Dou&le U *eld

Dou&le %e#el *eld

Dou&le 5 *eld



A++lica&le Welds for !ee $oint



A++lica&le Welds for La+ $oint

/lug slot*eld

S+ot seam*eld

Fillet*eld



A++lica&le Welds for Corner 5oint



A++lica&le Welds for Edge 5oint

Edge *eld



Edge /re+aration 8 Need

/oor+enetration

/oor strengt(

7ood+enetration

7ood strengt(9:;;< $ointe'cienc=



Edge /re+aration

Factors *(ic( in-uence c(oice of edge+re+aration

8 !(ic)ness

8 Material8 Welding +rocess8 E>tent of +enetration re6uired8 Welding distortion8 Cost



%utt $oint

S6uare 7roo#e*eld

Root



%utt $oint

Single V 7roo#e*eld

7roo#e angle

Root face

Rootga+



#arts of "elding joint•

!(roat• /enetration• Fusion• De+t( of fusion• Leg• Reinforcement

•

Root, root face, root ga+• 7roo#e• Weldment• Fusion ?one• 1eat a4ected ?one• %ead *idt(



$%ality of "elding joint

• Welding dimensions• !(roat

• Leg lengt(

• %ead *idt(

Leg

Leg




• Fusion

• /enetration




• Nice ri++les




• Clean $oint

• Less defects



Testing of "elding joint

• Fracture test

• tensile test




S%mmary• Welding dimensions

• !(roat

•

Leg lengt(• %ead *idt(

• Fusion

• /enetration

• Nice ri++les

• Clean $oint

• Less defects



Types of "elding

• Fusion *elding

• /ressure *elding

•

Non fusion *elding



&%sion "elding

• Manual metalArc *elding

• 7as metal arc*elding

• 7as *elding



#ress%re "elding

• Forge *elding

• Resistance*elding

• Friction stir

*elding



Non f%sion "elding

• No fusion• %ra?ing

• Soldering



&%sion "elding



Types of f%sion "elding

• MMAW @ Manual Metal Arc Welding

• 7MAW @ 7as Metal Arc Welding

M"7MA7 *elding

M"7 @ Metal "nert 7as *elding

MA7 @ Metal Acti#e 7as *elding• 7!AW @ 7as !ungsten Arc Welding

• !"7 @ !ungsten "nert 7as *elding

• SAW @ Su&merged Arc Welding

•

/lasma arc *elding• Car&on arc *elding

• 7as *elding

• Laser *elding



%AS"CS 0F WELD"N7

• WELD"N7 /ARAME!ERS

• /0LAR"!

• C0NS!AN! CURREN! Vs C0NS!ANV0L!A7E



WELD"N7 /ARAME!ERS

• CURREN!

• V0L!A7E

• ELC!R0DE !/E

• S1"ELD"N7 7AS FL0W RA!E



/0LAR"!

Straig(t +olarit @ DCEN

Electrode B#e

less fusion 9suita&le for t(in section=

More +enetration

suita&le for !"7 9a#oids &urning of tungsten=

Re#erse +olarit @ DCE/

Electrode #e

more common

more de+osition

less +enetration

arc is more sta&le



Constant current Vs constant#oltage

• Constant Current c(aracteristics

Manual Metal Arc Welding 9MMAW=

!ungsten "nert 7as Welding 9!"7=

• Constant Voltage Constant Current

7as Metal Arc Welding 97MAW=

Metal "nert 7as 9M"7= Metal Acti#e 7as

9MA7=

Su&merged Arc Welding 9SAW=



''!W ( 'an%al 'etal !r)Welding

SMAW @ S(ielded Metal Arc Welding



''!W ( 'an%al 'etal !r)Welding

*Travel dire)tion

Electrode

Arc+

Weld Puddle ,

Shielding Gas-

Solidified Weld Metal.

Slag/

SMAW @ S(ielded Metal Arc Welding

*Travel dire)tion

Electrode

Arc+Weld Puddle,

Shielding Gas-


Slag/



0'!W ( 0as 'etal !r) Welding

M"7 @ Metal "nert 7as *eldingMA7 @ Metal Acti#e 7as *elding



Basi) "elding parameters in0'!W

!(e &asic +arameters *(ic( re6uire to&e set in 7MAW +rocess are

• Current 9 am+s =

• Voltage 9 #olts =

• S(ielding gas -o* rate. 9 litres min =

•

Stic) out• !orc( angle

• Welding s+eed



TI0 WELDIN0



0T!W #RO1ESS



0T!W #RO1ESS

Fig 1a. TIG Arc



S!W ( S%merged !r) Welding



2ueries

discussions.....



T2an3 yo%



SMAW

0%5EC!"VES

!(e +rocess

/rocess #aria&les

Selection of consuma&les



SMAW

• Current -o*s t(roug( t(e electrodeca&le, to t(e electrode (older,t(roug( t(e electrode, and across t(e

arc• 0n t(e *or) side of t(e arc, t(e

current -o*s t(roug( t(e &asematerial to t(e *or) clam+ and &ac)to t(e *elding mac(ine

E$4I#'ENT !ND !11ESSORIES 4SED IN T5E #RO1ESS



GG /o*er source

GG Electrode (older

GG 7round ca&le

GG Welding ca&le

GG Lugs

50AWTI



H:

SMAW /rocess

*Travel dire)tion

Electrode

Arc+

Weld Puddle ,

Shielding Gas-


Slag/

LetIs ta)e a little closer loo) at t(eSMAW +rocessJ

*Travel dire)tion

Electrode

Arc+Weld Puddle,

Shielding Gas-


Slag/

E$4I#'ENT !ND !11ESSORIES



E$4I#'ENT !ND !11ESSORIES4SED IN T5E #RO1ESS

GG /o*er source

GG Electrode (older

GG 7round ca&le

GG Welding ca&le

GG Lugs

52AWTI

S2ielded 'etal !r)



S2ielded 'etal !r)Welding

#ro)ess 1apailities(Versatile pro)ess

Indoor 6 O%tdoor "elding

'%lti7position "elding

E8%ipment is simple 6 portale

4niversal pro)ess for repair "elding

Limitations( #rod%)tivity is less

9 &i:ed lengt2 of ele)trode

9 Deslaging53AWTI

LI'IT!TIONS O& S'!W #RO1ESS



LI'IT!TIONS O& S'!W #RO1ESS

>> Less metal deposition – Cannot be

used for heavy fabrication welding

>> Requires more number of welders

>> Control of distortion is difficult

>> Continuous & automatic Weldingis not possible

>> More strain to the welders

54AWTI

#OWER SO4R1E



#OWER SO4R1E

Either AC or DC may be used for SMAW process.

Factors to be considered for SMAW:

>> Type of current---- AC or DC

>> Current requirement

>> Positon of welding

>> Primary power available at the work station

55

SELE1TION O& ELE1TRODES



SELE1TION O& ELE1TRODES

>> Composition or Strength of BM.

>> Penetration requirement

>> Position of welding

>> Fit-Up condition

>> Skill of the welding personnel>> Cost of the welding operation

>> Service requirement of weld joint.

56AWTI

ldi l d



57AWTI

Welding electrodes

T2 El t d



H

T2e Ele)trode

•

"s a consuma&le 8 itgets melted during t(e*elding +rocess

• "s com+osed of t*o

+arts – Core Rod 9Metal Filler=

Carries *elding current

%ecomes +art of t(e *eld

–Flu> Coating

/roduces a s(ielding gas

Can +ro#ide additional3ller

Forms a slag

1L!SSI&I1!TION O& ELE1TRODES ;!WS . *=



1L!SSI&I1!TION O& ELE1TRODES ;!WS .<*=

E/>*>

Ele)trode

/> #si?>

@>

A>

*>>

**>

*+>

Weldingposition 1oating and

)%rrent )onditions

T#ES O& 1OVERIN0



Based of )overing(

9 R%tile ele)trodes

9 Basi) )oated ele)trodes

9 1ell%lose )oated ele)trode

9Iron po"derCiron o:ide ele)trodes

Based on appli)ation( 9 )aron7manganese steel ele)trodes !WS !.<*

9 Stainless steel ele)trodes !.<-

9 Lo" alloy steel ele)trodes !.<.

9 1opper 6 1opper alloy ele)trodes !.</

9 !l%mini%m 6 !l%mini%m alloy ele)trodes !.<*>

9 Ni)3el 6 Ni)3el alloy )overed ele)trodes !.<**

9 5ardfa)ing ele)trodes !.<*,

9 1overed ele)trodes for )ast iron !.<*.

60AWTI

15!R!1TERISTI1S O& ELE1TRODES



AWTI 61

R%tile Ele)trodes( 1ell%lose Ele)trode(

9 $%ite 6 smoot2 ar) 9 &or)ef%l 6 noisy ar)

9 E:)ellent slag removal 9 &riale slag

9 &ine ripples 9 1oarse ripples

9 'edi%m penetration 9 Deep penetration

9 T2i)3 slag 9 T2in slag )over 9 0ood r%nning 9 'ore gas s2ield

9 verti)al do"n

Basi) Ele)trodes(

9 !de8%ate penetration

9 Slag removal is good9 1ontains more iron po"der

9 0ood me)2ani)al #roperties

#4R#OSE O& &L4 1O!TIN0



#4R#OSE O& &L4 1O!TIN0>> Gas shielding of arc

>> Stabilizes the arc

>> Provides slag blanket

>> Alloying element will improve the mechanical

properties

>> Gives good appearance & penetration

>> Welding in all position is easy

>> Compensates for oxidation loss

62AWTI

1O'#OSITION O& &L4 IN T5E ELE1TRODE 1O!TIN0



1.Organic substance or Cellulose material:

Wood, Flour & Cellulose

High arc force Large volume of gas mostly hydrogen

2. Rutile:

Found in sand

Arc stabilizerGood slag former

3. Ball Clay:

Compound of silica & alumina

Slag former & Gives plasticity in the wet paste

63AWTI




4.Iron powder:

Gives good operating characteristics

Improves arc stability

Makes the coating electricallyconducting

5.Oxidizing Substance:

Makes the weld metal flow freely

Oxidizing substance are: iron oxide, Lamitite, Magnetite

6.Reducing Substances:

They compensate for manganese Ferro Silicon

Substances: Ferro Manganese, Ferro Silicon, Ferro Titanium

64AWTI




7.Ionizing Substances:

Used for stabilizing the arc

Substances : Chalk, Marble

8.Binding substance:

Help the coating to grip firmly around the core wire

Substances: Sodium Silicate, Potassium Silicate

65AWTI

'etal Transfer



&a)tors in%en)ing metal transfer(

9 S%rfa)e tension

9 &or)e of gravity 9 'agneti) for)es

9 'etall%rgi)al fa)tors

S%rfa)e tension for)es(

9 5olds t2e li8%id metal droplet to t2e tip<

&or)e to e over)om

&or)e of gravity(

9 #osition of "elding

&lat 777 5elps in metal transfer

Over2ead77Negative in%en)e oppose metal transfe

'agneti) for)es(

9LorentF 6 #in)2 for)es<

'etall%rgi)al fa)tors( 66AWTI

RE1O''ENDED S5!DE N4'BER O& T5E 1OLO4RED



8--9

10--11

12--14

EWG

Upto 100 Amps

100—300 Amps

Above 300 Amps

RE1O''ENDED S5!DE N4'BER O& T5E 1OLO4RED0L!SSES

Shade No.Range of welding

current(Amps)

67AWTI



68AWTI

Welding #ositions



Welding #ositions

GROOVE WELD

Flat position(1G)

Horizontal position(2G)

Vertical position(3G)

Overhead position(4G)

FILLET WELD

Flat position(1F)

Horizontal position(2F)

Vertical position(3F)

Overhead position(4F)

69AWTI



70AWTI



71AWTI



72AWTI

E&&E1T O& V!RI!TION O&#!R!'ETERS



#!R!'ETERS*<14RRENT TOO LOW(

• 4neven ead 2eig2t

•

#oor penetration• Slag in)l%sion

• Irreg%lar ripples

+<14RRENT TOO 5I05(

• Wide 6 at eads in %neven s2ape

• E:)essive penetration parent metal

• 'ore spatter

• #oor ripple appearan)e

• #orosity

• 4nder)%t

73AWTI




#!R!'ETERS,<!R1 TOO S5ORT(

• Irreg%lar ripple

• B%rn t2ro%g2

• 4ne8%al "idt2 6 2eig2t of ead

• Ele)trode freeFing t2e jo

-< !R1 TOO LON0( • 4ne8%al 2eig2t of ead

• Wide ripple

• 1rater "it2 lo" 2oles

• 'ore spatters

74AWTI




#!R!'ETERS. < TR!VEL TOO LOW(

• 'ore "idt2 6 2eig2t of t2e ead

• Slag in)l%sion

/< TR!VEL TOO &!ST(

• Narro" "idt2 of t2e ead

• #orosity

• Elongated ripples

75AWTI



76AWTI

!DV!NT!0ES O& S'!W #RO1ESS



>> Light & heavy gauge metals can be welded.

>> Fabrication welding, Construction welding &

Maintenance welding

>> All types of metals ( Ferrous, Non- ferrous & alloys)

can be welded

>> Welding operation is quick & easy

>> More suitable for short length welds

>> Less expensive

>> Less sensitive

>> It is portable

77AWTI

!##LI1!TIONS O& S'!W #RO1ESS



!##LI1!TIONS O& S'!W #RO1ESS

>> Used for welding thin & thick gauge metals

>> Used in welding bridges, bus bodies,domestic itemslike grills for gates, windows, chairs, doors .

>> Used in welding roof structure for workshop, broken

& cracked castings

>> Whenever welding is done in outdoor work, this

process is very useful as a diesel generator welding set can be used.

>> Used for hardfacing & repair welding

78AWTI



!(an) ou

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