Fatigue crack propagation in Hastelloy X weld metal · 2017. 2. 3. · in Hastelloy X Weld Metal . T. Weerasooriya . OAK RIDGE NATIONAL LABORATORY . CENTRAL RESEARCH LIBRARY . CIRCULATION

d OAK * ~

RIDGE NATIONAL LABORATORY

1 - - UNION 1 CARBIDE L

d

3 -

OPERATED BY UNION CARBIDE CORPORATIOM

DEPMTNIEIST OF ENERGY FOR M E IlblllTED STATES

ORNUTNl-6999

c

Fatigue Crack Propagation in Hastelloy X Weld Metal

T. Weerasooriya

OAK R I D G E N A T I O N A L L A B O R A T O R Y

. CENTRAL RESEARCH LIBRARY CIRCULATION SECTION .

4500N ROOM 175 L l6RARV LOAN COPV

~~ -

DO NOT TRANSFER TO ANOTHER PERSON I f you w i s h someone e l s e to s e e t h i s

report, send i n n a m e w i t h report and

t h e l i b r a r y w i l l ar range a loan. u C N 7969 S U 7 7 1

Prinlted in the United States of Almerica. Available from Natlilolnlal Technical Informlation ServDce

lia 22161 NTlS plrice codles-Pflinted Copy: A03 IMiIcrofiche A011

This report was prepared as an account of work sponsored by an agency of the United Stales Government. Neither the United States nor any agency thereof, nor any of thew employees. makes any warranty, expressed or imlplied, or assumes any legal liability or responsilbtlity for any third party's use or thie results of such use of any information. apparatus, product or process disclosed ifn this report, or represents that its use by such Chlird party WOUM not infringe privatety owned rights

I

1

ORNL/TM-6999 D i s t r i b u t i o n Category UC-77

Cont rac t No. W-7405-eng-26

METALS AND CERAMICS DIVISION

HTGK BASE TECHNOLOGY PROGRAM

GCR S t r u c t u r a l Materials S tud ie s (01332)

FATIGUE CRACK PROPAGATION I N HASTELLOY X WELD METAL

T. Weerasooriya

Date Published: November 1979

NOTICE This document contains information of a preliminary nature. I t i s subject to revision or correction and therefore does not represent a final report.

OAK RIDGE NATIONAL LABORATORY Oak Ridge, Tennessee 37830

ope ra t ed by U N I O N CARBIDE CORPORATION

U.S. DEPARTMENT OF ENERGY f o r the

CONTENTS

ABSTRACT e e 1

INTRODUCTION e , . . . 1

MATERIAL CHARACTERIZATION . . . . . . . . . . . . . . . . . . . . 2

Variables Governing Weldment Properties . . . . . . . . . . . 3

Material . . . . . . . . . . . . . . . . . . . . . . . 3

Joint design . . . . . . . . . . . . . . . . . . . . . 5

Welding process and welding parameters . . . . . . . . 5

Postweld heat treatment . . . . . . . . . . . . . . . . 5

Soundness of the welds . . . . . . . . . . . . . . . . 5

Experimental procedure . . . . . . . . . . . . . . . . 6

RESULTS AND DISCUSSION . . . . . . . . . . . . . . . . . . . . . . 10

CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . 21

I

iii

,/ /

/

FATIGUE CRACK PROPAGATION I N HASTELLOY X WELD METAL

T. Weerasooriya

ABSTRACT

The f a t i g u e crack growth rate of Has te l loy X weld metal increased with stress i n t e n s i t y , temperature , and inve r se f r e - quency. The r e s u l t s were c o r r e l a t e d wi th t h e equat ion

da dN - = ( A K ) ~ ,

f o r cons tan t frequency o r cons tan t temperature. The values of A and n were computed with a l i n e a r regress ion algori thm. With decreas ing frequency a t cons tan t AK and cons tan t t e m - p e r a t u r e (538OC) f a t i g u e crack growth rates approach an upper l i m i t . Fa t igue crack growth rate of t h e weld metal was lower than t h a t repor ted f o r base metal a t 538°C and lower a t 649°C f o r a frequency of 1 Hz.

INTRODUCTION

Has te l loy X , a Ni-Cr-Fe-Mo a l l o y (nominally 47, 23, 19, and 9 w t %,

r e s p e c t i v e l y ) , has been used success fu l ly f o r more than two decades i n

e levated-temperature a p p l i c a t i o n s r equ i r ing both oxida t ion r e s i s t a n c e

and high s t r eng th . It i s e s s e n t i a l l y a single-phase a l l o y with face-

centered cubic s t r u c t u r e . Strengthening is p r imar i ly by so l id - so lu t ion

a l l o y i n g wi th t h e elements chromium, molybdenum, and tungsten. However,

p r e c i p i t a t i o n of ca rb ide particles can a d d i t i o n a l l y s t rengthen t h i s

a l l o y .

I n t h e design of steam- and d i rec t -cyc le (gas t u r b i n e ) High-

Temperature Gas-Cooled Reactors (HTGRs), Has te l loy X has been suggested

f o r f a b r i c a t i o n of duc ts t h a t connect t h e r e a c t o r core t o t h e steam

genera tor o r gas t u r b i n e sec t ion . Also, t he a l l o y has been recommended

f o r thermal b a r r i e r cover p l a t e s surrounding t h e r e a c t o r core.

nominal design temperature f o r ho t duc ts , which c a r r y helium from t h e

The

1

2

r e a c t o r core t o the steam genera tor s e c t i o n , i s 788"C, with t h e possi-

b i l i t y of random short- term v a r i a t i o n s of temperature up t o 827OC. The

des ign nominal temperature of t h e hot gas i n t h e i n l e t of t h e ho t duc ts

f o r gas tu rb ine cycle HTGR i s 816°C.192 Has te l loy X i s a l s o one of t he

candida te materials f o r components of gas-cooled-reactor process hea t

p l an t s . I n these systems Has te l loy X could be used f o r duc t ing o r f o r

t h e tube o r suppor t -p la te material of t he in t e rmed ia t e and process hea t

exchangers. 9

I n the above a p p l i c a t i o n s f a b r i c a t i o n procedures r e q u i r e welding i n

t h e cons t ruc t ion of components, and t h e p r o p e r t i e s of t he weldment could

poss ib ly d i f f e r from those of t h e base metal. F a i l u r e s i n weldments are

o f t e n a t t r i b u t e d t o the growth of p r e e x i s t i n g flaws from f a t i g u e of

t h e s e components. I f one knows the rate of growth of s u b c r i t i c a l

c r acks , t h e p r e d i c t i o n of t h e l i f e of components conta in ing f laws is

poss ib le . This approach is p a r t i c u l a r l y u s e f u l f o r design and s a f e t y

a n a l y s i s .

This document provides s u b c r i t i c a l crack growth da ta on Has te l loy X

weld'metal. Test samples were obta ined from weldments t h a t were f a b r i -

ca t ed by welding two Has te l loy X p l a t e s wi th Has te l loy X f i , l l e r metal.

MATERIAL CHARACTERIZATION

Specimens f o r t h i s s tudy were f a b r i c a t e d from solut ion-annealed

12.5-mm-thick Has te l loy X p l a t e s (hea t 2600-4-4284) purchased from

Cabot -Ste l l i t e . The mechanical p r o p e r t i e s of t h i s hea t are:

Heat t reatment solut ion-annealed a t 1177°C fol lowed by r ap id coo l

U l t i m a t e tensi le s t r e n g t h , MPa 790

0.2% y i e l d s t r e n g t h , MPa 345

Elongat ion i n 25 mm, % 49

3

The chemical composition of the Hastelloy X plates is:

El emen t Content, wt % Element Content, wt %

Ni Balance co 2.40

Cr 21.79 Mn 0.59 W 0.63 Mo 8.82

Fe 19.06 P 0.018 C 0.06 S C0.005

Si 0.35 B <0.002

Details of weldment fabrication are discussed later in this report.

Figure 1 shows microstructures of the weldment. Second-phase micro-

constituents are probably carbides of the QC type with a lattice

constant of 10.995 (ref. 3). In areas close to the fusion line, Hastelloy X base metal has a larger concentration of these coarse car- bides [Fig. l(b)l.

Variables Governing Weldment Properties

Data obtained from one weldment may differ from the data obtained

from another weldment for several reasons.

Material

Chemical composition can influence the elevated-temperature proper-

ties of a ~eldment.~,5

dictates the composition of the weld metal, base metal dilution, fluxes, and cover gas all contribute to the final deposit composition. In this

study chemical composition of the weld metal (heat 2600-4-4345) with 1.56-mm-diam Hastelloy X wire for filler is:

Although the filler metal composition nominally

Element Content, wt % Element Content, wt %

Cr 21.92 Ni Balance

W 0.42 Mn 0.70

Fe 18.81 Mo 8.85

C 0.08 P 0.022

Si 0.40 S < 0.005

co 2.09

4

a,

D

a a,

4

(d

a, 3 2

5

J o i n t design

The geometry of t h e j o i n t can l ead t o d i f f e r e n t r e s i d u a l stress

p a t t e r n s , s t r u c t u r e s , and p r o p e r t i e s of t h e welds. Weldments were

f a b r i c a t e d wi th a V-groove of 75" included angle.

Welding process and welding parameters

The gas tungsten-arc (GTA), gas metal-arc (GMA), sh i e lded metal-arc

(SMA), and submerged-arc (SA) welding processes are most commonly used

i n jo in ing nuc lear power components. These processes can produce welds

wi th d i f f e r e n t m e t a l l u r g i c a l s t r u c t u r e and p rope r t i e s . Even wi th a

g iven process , v a r i a t i o n i n welding parameters and techniques , such as

c u r r e n t , vo l t age , t r a v e l speed, e l e c t r o d e s i z e , number and sequence of

pas ses , amplitude, frequency, p o l a r i t y , and shape of app l i ed vo l t age ,

may l ead t o d i f f e r e n t p r o p e r t i e s of t h e weldments . , Weldments were made with the fol lowing parameters:

Welding process GTA

Speed 3.75 x lo4 mm/s (625 mm/min)

Voltage 9-9.5 v Passes 7

Current 195 A

S t r a i g h t p o l a r i t y

Elec t rode 2.34 mm i n diameter , 30" inc luded angle

Postweld hea t t rea tment

Welds in nuclear a p p l i c a t i o n s are hea t - t r ea t ed many t i m e s t o a l t e r

m e t a l l u r g i c a l s t r u c t u r e o r t o r e l i e v e r e s i d u a l stresses. However, t h e

weldment t h a t was f a b r i c a t e d f o r t e s t i n g i n t h i s program w a s no t post-

weld hea t - t rea ted .

Soundness of t h e welds

Defec ts , such as i n c l u s i o n s , po ros i ty , and incomplete fus ion , can

degrade t h e p rope r t i e s . The weldment was radiographed, and no d e f e c t s

were indica ted .

6

Experimental procedure

Standard (ASTM E 6 4 7 ) compact t ens ion (CT) specimens were prepared

from weldments t h a t were f a b r i c a t e d as o u t l i n e d above. The dimensions

of t h e specimens’are given i n Fig. 2. The notched area of t h e specimen

w a s l o c a t e d a t t h e c e n t e r of t h e weld metal such t h a t t h e major a x i s of

t h e weldment coincided with the major a x i s of t he notch. The base metal

w a s o r i e n t e d such t h a t t h e r o l l i n g d i r e c t i o n w a s perpendicular t o t h e

plane of crack gro,wth.

ORNL-DWG 79- 10401

HASTELLOY X

HASTELLOY X

Fig. 2. Dimensions i n Millimeters of t he Compact Tension (CT) Specimen with the Weldment.

Specimens were precracked a t room temperature with a servo-

h y d r a u l i c t e s t i n g machine. Precracking w a s performed wi th a s i n o s o i d a l

waveform and was terminated when a value f o r maximum stress i n t e n s i t y

7

(&ax) s l i g h t l y smaller than the i n i t i a l Kma, f o r t h e tests w a s reached.

The r a t i o ( R ) of Kmin t o K,,, w a s kept a t 0.05 throughout a l l t h e tests.

The machine se tup used f o r elevated-temperature f a t i g u e growth

t e s t i n g is shown i n Figs. 3 and 4.

closed-loop, servo-control led e l e c t r o h y d r a u l i c MTS t e s t i n g machine,

employing a t r i a n g u l a r waveform. The tests were conducted i n a i r wi th

a stress r a t i o value (Pmin/Pmax) of R = 0.05 (according t o ASTM E 647,

u n l e s s s t a t e d otherwise) . Induct ion hea t ing maintained t h e e l eva ted

temperature during f a t i g u e t e s t i n g . Specimen temperature w a s c o n t r o l l e d

t o 4l0C, while t h e temperature v a r i a t i o n along t h e path of t h e crack w a s

less than 6'C. Crack l eng ths were measured o p t i c a l l y wi th t r a v e l i n g

microscopes a t p e r i o d i c i n t e r v a l s .

A l l tests were conducted on a

Crack growth rates were computed by f i t t i n g a continuous cubic

s p l i n e curve t o t h e average crack l eng th dataO7 The c loseness of t h e

.I-

- i n

Fig. 3. The Tes t ing Machine. Induct ion h e a t i n g was used t o main- t a i n temperature.

8

Fig. 4. Close-up of Heating Coil in Testing Machine.

fitted cubic spline curve to the experimental points was determined by

the variable S in Eq. (1):

N

i=1 [ai - ai(fit)12 = S2N , (1)

where

ai = measured crack length, and

ai(fit) = fitted crack length.

9

The s p l i n e curve w a s f i t t e d t o s a t i s f y t h e above equation.

y s i s S w a s taken as 0.025 mm and can be considered as a measure of t he

confidence of t he o p t i c a l readings. The stress i n t e n s i t y expression

used t o c a l c u l a t e LW was as fol lows:

I n t h i s anal-

0 . 5 1 . 5 2 . 5 AK = jqj-j[ 29 a 6 (i) - - 185.5(;) + 655.7(;)

- 1017(;) 3 . 5 + 638.9(;)4*5] ,

where

AI’ = cycl ic load range ( i .e . , Pmax - Pmin),

a = crack l eng th ,

B = specimen th i ckness , and

W = specimen width.

The tests were terminated a t t h e onset of permanent crack opening.

A computer code w a s prepared and used t o c a l c u l a t e growth rates and

p l o t growth vs A K , as discussed above.

least squares r eg res s ion l i n e f o r daldN vs AK p l o t s and c a l c u l a t e A and

n i n t h e equat ion

The computer code w i l l f i t a

where - - $ - crack growth i n mm/cycle, and

AK = stress i n t e n s i t y i n MPafifor each p l o t .

We conducted tests t o f i n d t h e v a r i a t i o n of s u b c r i t i c a l crack

growth rates with varying temperatures a t 1 Hz. Tests were conducted a t

538, 650, and 760°C. Also, tests were conducted t o f i n d t h e behavior of

c r ack growth rates with f r equenc ie s of 0.1, 1 , and 10 Hz a t 538°C.

10

RESULTS AND DISCUSSION

We c o r r e l a t e d crack growth da ta wi th Eq. (3) . Figures 5 through 7

g i v e the daldN vs AK da t a on loga r i thmic coord ina te s f o r t h e tests con-

ducted t o f i n d out t h e e f f e c t of temperature on f a t i g u e crack growth

rates f o r a cons t an t frequency. These f i g u r e s a l s o g ive both t h e l i n e a r

r e g r e s s i o n l i n e s f o r t h e s e d a t a and t h e values of A and n i n Eq. ( 3 )

(daldN - mmlcycle; AK - MPafi) f o r t h e r eg res s ion l i n e s .

band f o r weld metal i s on t h e o rde r of p l u s o r minus twice t h e p red ic t ed

va lues by t h e r eg res s ion l i n e . This probably r e s u l t e d from t h e ani-

so t ropy and inhomogeniety of t h e weld metal. Figure 8 g ives a com-

pa r i son of t h e v a r i a t i o n of f a t i g u e crack growth rate wi th temperature

a t 1 Hz. A s observed f o r most of t h e materials, crack growth ra te

i n c r e a s e s wi th i n c r e a s i n g temperature f o r Has te l loy X weld metal. One

exp lana t ion is t h a t as temperature i n c r e a s e s d e t e r i o r a t i o n of t h e crack

t i p from ox ida t ion i s higher. However, a t higher stress i n t e n s i t i e s

d i f f e r e n c e s i n crack growth rates from temperature become smaller. A t

h i g h e r growth rates unoxidized metal i s r a p i d l y exposed, and hence oxi-

d a t i o n a t t h e crack t i p has l i t t l e e f f e c t on growth rate. F igu res 5 and

6 compare t h e f a t i g u e crack growth rates of weld metal and base metal.

A t both 538 and 650°C base metal has a higher crack growth ra te compared

t o t h a t of weld metal.

growth rates of base m e t a l and weld metal i n c r e a s e s w i t h i n c r e a s i n g

stress i n t e n s i t y f a c t o r .

The s c a t t e r

A t 650°C t h e d i f f e r e n c e of t h e f a t i g u e crack

Figures 9 and 10 g i v e t h e f a t i g u e crack growth ra te d a t a , f i t t e d

r e g r e s s i o n l i n e , and values of A and n f o r f u r t h e r tests conducted on

weld m e t a l t o f i n d t h e e f f e c t of frequency on f a t i g u e crack growth rates

a t 538°C.

growth rate of weld metal a t 538OC.

growth rate i n c r e a s e s with decreasing frequency. I n t h e range of f r e -

quencies between 0.1 and 1 Hz, t h e d i f f e r e n c e i n t h e f a t i g u e crack

growth rate (FCGR) is not s u b s t a n t i a l , but t h e d i f f e r e n c e i n crack

growth rates between t h e f r equenc ie s of 10 and 0.1 Hz o r 10 and 1 Hz is

g r e a t e r .

Figure 11 compares t h e e f f e c t of frequency on f a t i g u e crack

In gene ra l , t h e f a t i g u e crack

11

ORNL-DWG 78-18702R

D K . STRESS INTENSITY FACTOR ( K s i f i . 1

to 20 30 40 50 60 70 80 10-2

ENVIRONMENT : AIR 1 0 - ~

t 0-3

1 0 - ~

10-6

W -I V t V \ E E Y

W l- a a I I-

g a W Y V a a V

i 0 \ 0 0

4 o - ~

- - HASTELLOY X

WELD METAL-

A K . STRESS INTENSITY FACTOR ( M P o f i )

W I- a. a I I-

g a W

Y V

V

a a

i U \ 0 0

Fig. 5. Fa t igue Crack Growth Rate of Has te l loy X Weld Metal a t 538OC and 1 Hz. Base metal data is from: C. R. Brinkman e t a l . , Application of Hastetzoy X in Gas-Cooled Reactor Systems, ORNL/TM-5405 (October 1976). Note t h a t S I u n i t s were employed i n t h e development of t h e above equat ion.

1 2

ORNL- DWG 78- 22316R

10-2

10-3

W -J V t V \ E E Y

I I-

Lz a

i \o 'p

10-5

A K , STRESS INTENSITY FACTOR ( K s i f i . 1

10 20 30 40 50 60 70 80

I ' I ' I I I I I ' I ' I 'I I

I I I I ' I l l

TEMPERATURE = 649 4: I 0 I l l FREQUENCY = 1 Hz I O I I I

IRONMENT : AIR 10-7.77 ( ~ ~ ) 3 . 0 0

I 1 I I 0

WELDED SPECIMEN ORIENTATION

0

L: HASTELLOY X t WELD METAL '-...--

1 0 - ~

W

t a

Y V Q CL V

10-6 i \o U

10-6 I O ' 20 40 60 00 I O 2

OK. STRESS INTENSITY FACTOR (MPo ./& 1

Fig. 6. F a t i g u e Crack Growth Rate of Has te l loy X Weld Metal a t 649°C and 1 Hz. Base metal d a t a is from: C. R. Brinkman et a l . , Application of Hastelloy X i n Gas-Cooled Reactor Systems, ORNL/TM-5405 (October 1976).

13

ORNL-DWG 78-22317

AK, STRESS INTENSITY FACTOR ( k s i f i . ) 10 2 0 30 40 50 60 70 00

AK. STRESS INTENSITY FACTOR ( M P o f i )

Fig. 7. Fa t igue Crack Growth Rate of Has te l loy X Weld Metal a t 760°C and 1 Hz.

14

ORNL-DWG 78-22318

AK, STRESS INTENSITY FACTOR (Ks i&)

40 20 30 40 50 60 70 00 40-2

1 0 - ~

- LL' -I V * V

W J V t V \

E E 10-5 2 t !3 a

I t ~ - ~ I-

2

- W

W

a I

I-

a (3

Y V

V

a L 3

Y V U a V

a a

\o \

2 to-6 g 0

0 D

4 o - ~

WELD METAL

t 0-7

10-6 40' 20 40 60 80 402

P K . STRESS INTENSITY FACTOR ( M P a f i )

Fig. 8. E f f e c t of Temperature on Fa t igue Crack Growth Rate of Has te l loy X Weld Metal a t 1 Hz.

15

W J

V \ Y E E -

I c

i 0 \ 0 0

20 40 60 00 102 AK, STRESS INTENSITY FACTOR (MPo 6)

Fig. 9. 538°C and 0.1

Fa t igue Crack Growth Rate of Has te l loy X Weld Hz . Metal a t

16

10-2

E -

ORNL-DWG 79-9898

AK, STPESS INTENSITY FACTOR ( K s i f i 1 10 20 30 40 50 60 70 00

TEMPERATURE = 538°C

VIRONMENT : AIR

1 0 - ~

-

I c

20 4 0 60 80 102 AK. STRESS INTENSITY FACTOR ( MPa f i )

Fig. 10. Fa t igue Crack Growth Rate of Has te l loy X Weld Metal a t 538OC and 10 Hz.

17

ORNL-DWG 79 - 9250

W

Lz 5 I I-

a (3

Y V

m V

a

A K . STRESS INTENSITY FACTOR ( K s i f i )

10 20 30 40 50 60 70 80 10-2

10-3

IO -4

A K . STRESS INTENSITY FACTOR ( MPo 6)

1 o - ~

IO-^

Y

Fig. 11. E f f e c t of Frequency on Fa t igue Crack Growth Rate of Has te l loy X Weld Metal a t 538°C.

18

The p r i n c i p a l causes of t h e e f f e c t of frequency are aga in bel ieved

t o be: ( 1 ) t h e increased ox ida t ion a t t h e crack t i p , and ( 2 ) t h e t ran-

s i e n t creep t h a t occurs during the longer cyc le per iods a t t h e lower

f requencies . There a p p e a r s t o be an upper l i m i t of c rack growth rate

f o r decreas ing frequency. When t h e frequency i s reduced t h e r e may be a

s t a g e a t which increased environmental a t t a c k is balanced by t h e

b lun t ing and stress r e l a x a t i o n a t t h e crack t i p and hence a reduct ion of

t h e d r iv ing f o r c e aK a t the crack t i p . Figure 12 shows r e p r e s e n t a t i v e

areas of t h e f r a c t u r e sur face . These c l e a r l y show t h e fat igue-induced

s t r i a t i o n s on t h e crack s u r f a c e and how these s t r i a t i o n conf igu ra t ions

seem t o d i f f e r . This i s expected as weld metal does not have a homo-

geneous s t r u c t u r e ( a s a r e s u l t of mul t ipass welding, i nc lud ing o s c i l -

l a t i o n i n any given pass) .

Figure 13 shows a t y p i c a l o r i e n t a t i o n of the f a t i g u e crack wi th

r e s p e c t t o t h e mic ros t ruc tu re of t he weld metal. Cor re l a t ion of crack

conf igu ra t ion and mic ros t ruc tu ra l d e t a i l s w a s no t de t ec t ed , though on a

few occasions t h e crack tends t o change d i r e c t i o n t o make t h e d e n d r i t e s

p a r a l l e l i n the s t r u c t u r e .

CONCLUSIONS

This r epor t p re sen t s the r e s u l t s of p a r t of a broad program of

s tudy on FCGR p r o p e r t i e s f o r HTGR a p p l i c a t i o n s . We discussed r e s u l t s of

t h e c h a r a c t e r i z a t i o n of f a t i g u e crack growth i n a i r f o r Has te l loy X weld

metal. We concluded t h e fo l lowing from the r e s u l t s :

1 . The FCGR i n weld metal i nc reases wi th inc reas ing temperature a t

1 Hz i n t h e range 538 t o 760°C.

2. The FCGR f o r weld metal decreases wi th inc reas ing frequency

from 1 t o 10 Hz a t 538°C. Also, t h e r e i s an upper l i m i t growth rate f o r

decreas ing frequency a t a cons tan t AK value.

3. The FCGR of base metal i s h igher than that of weld metal both

a t 538 and 649°C f o r frequency of 1 Hz.

19 d

03 c

r"

5

0

a( c

I

0

CT c3 Y

O

5 "t LL 0

Z 0

I- O W

CT

-

-

n

20

DIRECTION OF WELDING -

Fig. 13. Orientation of Two Locations of a Typical Fatigue Crack with Respect to the Microstructure.

2 1

ACKNOWLEDGMENTS

. The au tho r g r a t e f u l l y appreciates t h e h e l p and pa t i ence shown by

J. P. S t r i z a k dur ing t h e i n i t i a t i o n pe r iod of t h i s t e s t i n g program.

The r e p o r t was reviewed by M. K. Booker and R. W. Swindeman, e d i t e d

by B. G. Ashdown, and prepared f o r f i n a l p u b l i c a t i o n by P. T. Thornton.

REFERENCES

1. P. L. Ri t tenhouse , Initial Assessment of the Status of HTGR Metallic

Structural Materials Technology, ORNL/TM-4760 (December 1974).

2. C. R. Brinkman e t a l . , Application of Hastelloy X in Gas-Cooled Reactor Systems, ORNL/TM-5405 (October 1976).

3. G. Y. L a i , "An I n v e s t i g a t i o n of t h e Thermal S t a b i l i t y of a

Commercial Ni-Cr-Fle-Mo Alloy (Has te l loy X ) , " Metall. Trans. A 9A:

827-33 (1978).

4. R e T. King, D. A. Canonico, and C. R. Brinkman, "Elevated-

Temperature Weldment Behavior as Rela ted t o Nuclear Design

Criteria," Weld. J. (Miami) 54(8): 265-s-275-s (August 1975).

5. F. C. Hul l , "The E f f e c t of Composition on t h e Stress-Rupture

P r o p e r t i e s of F u l l y A u s t e n i t i c S t a i n l e s s S t e e l Weld," paper pre-

s e n t e d a t F i r s t Na t iona l Congress on P res su re Vessels and Pip ing ,

San F ranc i sco , C a l i f . , May 10-12, 1971.

6. G. M. Goodwin, N. C. Cole, and G. M. S l augh te r , "A Study of Ferri te

Morphology i n A u s t e n i t i c S t a i n l e s s Steel Weldments," Wetd. J. (Mhni) 51(9): 425-s-429-s (September 1972).

T. Weerasooriya, Fatigue Crack Propagation in the Heat-Affected Zone of 2 1 / 4 Cr-1 Mo Steel and ERNiCr-3 Weldments -Interim Report, ORNL/TM-6971 ( i n p r e s s ) .

7.

I

23

ORNL/TM-6999 D i s t r i b u t i o n Category UC-77

INTERNAL DISTRIBUTION

1-2. 3.

4-5. 6. 7. 8. 9. 10. 11. 12. 13.

14-16. 17. 18. 19. 20.

C e n t r a l Research L ib ra ry Document Reference Sec t ion Laboratory Records Department Laboratory Records, ORNL, R.C. ORNL Pa ten t Sec t ion M. K. Booker C. R. Brinkman C. W. C o l l i n s B. E. Fos t e r G. M. Goodwin M. L. Grossbeck M. R. H i l l J. A. Horak R. R. Judkins P. R. Kasten E. H. Lee

21. 22. 23. 24. 25. 26.

27-3 1. 32. 33. 34. 35. 36. 37. 38. 39. 40.

K. C. Liu H. E. McCoy R. K. Nanstad P. L. Ri t tenhouse G. M. Slaughter J. H. Smith J. P. S t r i z a k R. W. Swindeman V. J. Tennery F. W. Wiffen R. W. B a l l u f f i (Consu l t an t ) A. L. Bement, Jr. (Consul tant) W. R. Hibbard, Jr. (Consultant E. H. Kottcamp, Jr. (Consultan M. J. Mayfield (Consul tant) J. T. S t r i n g e r (Consul tant)

EXTERNAL DISTRIBUTION

41-42. DOE, DIVISION OF NUCLEAR POWER DEVELOPMENT, Washington, DC 20545

Direc to r

43. SAN-DEVELOPMENT, SAN DIEGO AREA OFFICE, P.O. Box 81325, San Diego, CA 92138 Senior Program Coordinator

44. DOE SAN FRANCISCO OPERATIONS.OFFICE, 1333 Broadway, Wells Fargo Building, Oakland, CA 94612

Manager

45-46. DOE, OAK RIDGE OPERATIONS OFFICE, P.O. Box E , Oak Ridge, TN 37830 A s s i s t a n t Manager, Energy Research and Development

D i r e c t o r , Nuclear Research and Development

47-219. DOE, TECHNICAL INFORMATION CENTER, P.O. Box 62, Oak Ridge, TN 37830

For d i s t r i b u t i o n as shown in TID-4500 D i s t r i b u t i o n Category, UC-77 (Gas-Cooled Reactor Technology).

* U. S. GOVERNMENT PRINTING OFFICE: 1979-640-245-294