s' Sheet'l of 29

s. .

| Metallurgical Analysis

of

Failed Turbine Casing Bolt

from

Arkansas Power & Light, I tit 1

Report No. IE-120

September 9, 1980

.

.

Prepared for: United States NuclearRegulatory Commission 1

Office of Inspection jand Enforcement '

NRC Contract 05-80-251gt tfhp PAR: NRC-IE-80/81, Task 04

.$ \ N ''s,

THO'AAS 1. h7E j' PROFT i 5 a?, 3 i 15729 ( G5 by: M f) -~~ 0 (AtlLWAUKEE M' Thomas L. Proft, W E. [ V4

% Technimet Corporationf%L*

Illlstilf" for: PARAMETER , Inc.Consulting EngineersElm Grove, Wisconsin

,

as12100 OD.__ -- . __ . . __ _

s

a r=b an s* $ e r,' n c.C O N $ U til N G E N GIN f f R 5ftM G R O V E, wl1 CON 5tN

NOTICE

This report was prepared as an accountof work sponsored by an agency of theUnited States Government. Neither theUnited States Government nor any agencythereof, or any of their employees, makesany warranty, expressed or impl ied , or

' assumes any legal liability or responsi-bility for any third party's use, or theresults of such use, of any information,apparatus, product or process disclosedin this report, or represents that itsuse by such third party would not infringeprivately owned rights.

I

,

.

CO T O

4379 SOUTH HOWELL AVENUEMILW AU K E E. WISCONSIN 6320/

414:4 b3 0054

TEGINIhET REPORT NO. 76429

PARAMETER REPORT NO. IE-120

.

SUBJECT: ANALYSIS OF FAILED TURBINE CASINGBOLT FROM ARKANSAS POWER AND LIGilT,UNIT 1. NRC CONTRACT 05-80-251,PAR: NRC-IE-80/81. TASK ORDER NO. 4

|

BY: Til0 MAS L. PROFT, P . ii .

DATE: SEPTEMBER 9, 1980

1

|

|

|

|

|

.

/ \'

y OO ,__3.5 _ft_LI_V_

g i5__

CORPQRATIONs ,

4379 SOUTH HOWE LL AVENUEM ILW A U K E E. WISCONSIN 53207

September 9, 1980 414/481 0054

REPORT NO. 78429

I. DESCRIPTION AND PURPOSE:

A failed 3/4" diameter fastener was submitted. The fast -ener was identified as a bolt, but was by definition astud, with a nut at each end. The stud had fractured onone of the threaded ends at what appeared to be the firstengaged thread.

This stud was reportedly removed from a flange on the tur--bine casing of the emergency steam drive auxiliary feed-water pump at Arkansas Power and Light Company, Unit 1.The Arkansas Power and Light Company had reported to the.RC-IE that a steam leak was observed at this connection.Visual inspection had found five out of a total of eightstuds had failed. The failed studs were consecutivelylocated on the flange, reportedly from the 7 o' clock to1 o' clock positions. It was also reported that the tur-bine had experienced an overspeed recently. Previousproblems had been reported with water slugging, which mayhave caused vibrations or excessively high loads in thesystem.

The studs were reportedly to have been manufacturedaccording to ASTM A-193 Grade B7.

The purpose of this investigation was t'o provide metal-lurgical analysis of the failure, as outlined in ContractNumber NRC-05-80-251, Task Order No. 4.

II. CONCLUSIONS:

A. The stud material did not conform to that specifiedIfor ASTM A-193 Grade B7, which requires a quenched ;

and tempered 4100 series alloy steel. Microstructuraland chemical analyses showed the material to be colddrawn AISI 1215.

.

* Sqptember 9, 1980,

REPORT NO. 78429

Page 2.

1I. CONCLUSIONS: (Continued)

B. Based on Rockwell B hardness tests, the estimatedtensile strength of this material is 90,000 psi.Estimated yield strength is approximately 70,000 psi.The specified AST!! A193 Grade B7 material requiresa minimum tensile strength of 125,000 psi and a mini-mum yield strength of 115,000 psi.

C. Scanning electron microscopy showed that failureoccured primarily by brittle transgranular (cleavage)fracture. Some areas of mixed mode intergranular,transgranular, and ductile dimpling fracture were alsofound.

D. EDAX analysis on the fracture face and adjacent'

threads showed the corrosion products to contain cal-cium, potassium, silicon, aluminum, magnesium, and smallamounts of sulfur, chlorine, and phosphorous. Itappears that these corrosion products are the resultof exposure to steam and the surrounding insulationmaterial after fracture occured. Corrosion was not acausative factor in this failure.

E. No evidence of corrosion pitting or fatigue crackingwas found in the adjacent threads or on the otherthreaded portion of the stud.

F. Failure appears to have occured by brittle fracture,initiating at three different points along the rootof the first engaged thread. Failure probablyoccured in less than 10 cycles.

G. The cold drawn 1215 material used would be expectedto have much lower resistance to the type of frac-

.

ture found than the specified ASTM A-193 Grade B7 Imaterial.

'

11. Only one of the five failed fasteners was submittedfor analysis, and therefore no conclusions can bedrawn as to the mode of failure in the other four studs .

i

, _ _ - _ -- .-|

___ . . - .

.

*

September 9, 1980

REPORT NO. 78429

Page 3.

,

III. TESTS AND RESilLTS:

A. Visual Examination.,

Figures 1 through 4 show the failed stud as received.Note that fracture occured along what appears to bethe first engaged. thread.

Figure 5 shows the fracture surface as received. Theheavy layer of corrosion product s and pipe insulationmaterial prevented any fractographic analysis at thispoint.

Figure 6 shows the unfailed threaded portion of thestud after removal of the nut. Stereo-microscopeexamination of the thread roots and subsequent cican--ing and dye penetrant inspection could reveal nocracking on this end of the stud.

B. Energy.Dispersive X-ray Analysis Before Sectioning.

Before the stud was occtioned, energy dispersiveX-ray analysis was performed on the material in the ,roots of the exposed threads of the unfractured end.Figure 7 shows the electron image of the area analy::ed.

Figure 8 details the results o f semi-quantitativeanalysis at the point indicated by the arrow in Figure 7The analysis shows unusu,11y high levels of silicon,phosphorous, molybdenum, co?cium and capper. Onlytraces of sulfi.r and chlorine vere found.

C. Energy Dispersive X-ray Analysis of Fracture SurfaceAfter Sectioning.

Figure 9 shows the stud after sectioning. Section Bwas used for hardness testing and metallography.'

Section C was used f'or spectrographic chemical analy-sis. Section D, containing the fracture surface , wasused for EDAX analysis, scanning electron microscopyand subsequent metallography.

.

Figure 10 shows the electron image of the area at thealzow in Figure 5.

i

I

|,

|. ..

.

.

'

Se'ptember 9, 1980

| Rl! PORT NO. 78429

Page 4.

III. TESTS AND RESULTS: (Continued)

C. EDAX Analysis of Fracture Surface Af ter Sectioning.TContinneil)

The area indicated by the arrow is shown at highermagnification in Figure 11. The corrosion productsin this area were EDAX analyzed, the results of whichare detailed in Figure 12. The high aluminum andsilicon found are presumably f rom the steam pipinginsulation material. The calcium and potassium arethe result of exposure to the 1ive steam. Sulfur andchlorine, while present, are not at levels expectedto initiate a corrosion induced fa ilure.

Figure 13 shows one of the fibers visible in the lower.left of Figure 11. EDAX analysis of this fiber is de-tailed in Figure 14. The analysis indicates the fibermay be asbestos, although contamination by the steamand su'osequently formed corrosion products preventaccurate assessment of the magnesium, calcium and iron

; ratios, which are used to identify asbestos.

i Figure 15 shows the corrosion product on a typical'

area of the fractu.e. This heavy layer of corrosionprevented any fractographic analysis before cleaning.Figure 16 is an EDAX analysis of this area. The re-

| sults are typical of several other areas on the frac-! ture face.

D. Spectrographic Chemical Analysis.

The following details iresults of st ec trographic chemi-cal analysis performed on cross section C of the stud:

Element Percentage

C .09Mn 1.12S .341P .091Si 4 01Cr .03Ni .02Mo 4 01Pb 4 01Cu .02

.

.

~

September.9, 1980

REPORT NO. 78429

Page 5.

III. TESTS AND RESULTS: (Con t inued)

D. Spectrographic Chemical Analysis. (Continued)

The material conforms to the check analysis limitsof SAE or AISI 1215 material. This material is a re-sulfurized, re-phosphorized grade of carbon steelused primarily for its free machining properties.Due to the high phosphorous and sulfide stringer con-tent, this material is not recommended for criticalhigh strength applications.

E. Meta 11ography on Bolt Shank.

Figures 17 and 18 show the microstructures found ontransverse and longitudinal samples prepared from'

section B. The structure consists primarily offerrite, with small patches of pearlite and largemanganese sulfide stringers. This structure is typi-cal of an SAE 1215 material. To verify the composi-tion of the inclusions, the polished longitudinal

tion was examined with the scanning electron micro-_ cope in the hackscattered and X-ray mapping modes.

Figure 19 shows the backscattered electron image ofone of the stringers.

Figure 20 is a sulfur X-ray map of this same area.The concentration of sulfur X-ray signals verifiesthe inclusion is a sulfide.

F. Hardness Testing.

Rockwell B hardness tests were taken at mid-radius ona cross section of the bolt shauk. Hardnesses at900 interva 'anged from Rkw B89.5 to Rkw B91.2.From these hardness tests, the tensile strength isestimated to be approximately 90,000 psi. The speci-fied material, ASTM A-193 Grade B7 requires a .nini-mum tensile strength of 125,000 psi. While a ninimumhardness is not stated in the ASTM speci ficat ic n , hard- :ness level at a tensile strength of 125,000 psi would |be approximately Rkw C25. !

l1

u

4

|

|1

September 9, 1980 ('

)RiiPORT NO. 78429

Page 6.

III. TESTS AND RESULTS: (Continued)

F. liardness Testing. (Continued)

The hardness level and microstructure indicates thatthe m.iterial is cold drawn. While this would elevatethe vield strength to anproximately 70,000 psi, theductility and resistance to brittle fracture would befurther degraded.

G. Scanning Electron Microscopy on Fracture Surf ace A f terCleaning.

In order to determine the mode of failure, the frac-ture surface was cleaned in a mixture of phosphoricacid and glycol, with subsequent rinsing and ultra-.sonic cleaning in acetone.

Figure 21 shows the appearance of the fracture surfaceafter these cleaning operations. The letters refer toareas examined by scanning electron microscopy.

The electron image of region A is shown in Figure 22.

Figures 23 and 24 show the fracture features withinthe crescent shaped area of region A on Figure 22.Fracture in this area is primarily by transgranularcleavage, with some indications of intergranularcracking. Pitting on the cicavage planes was causedby corrosion subsequent to fracture and partially bythe phosphoric acid cleaning solution.

Figure 25 shows the fracture features found in regionB of Figure 21. Again, at this location, fracturewas primarily by transgranular cleavage.

Figure 26 shows the fracture features at region C ofFigure 21. Again, failure is primarily by transgranu-iar cleavage, with some indications of intergranularcracking.

Figure 27 shows the electron image of region D.Macroscopic features indicate this to be the primaryorigin of fracture.

- _

.

'

September 9, 1980

REPORT NO. 78429

Page 7.

III. TESTS AND RESULTS: (Continued)

G. SEM on Fracture Surface Af ter Cleaning. (Continued)

Figure 28 shows this region at higher magnification.Failure is primarily by transgranular cleavage, withsmall areas of ductile overload and some intergranularcracking evident.

Figure 29 shows the fracture features at region E.Again, failure is primarily transgranular with someindications of intergranular cracking.

Figure 30 shows region F at low magnification. Thisarea is shown at higher magnification in Figure 31.Again, fracture is primarily by cleavage, with some-evidence of intergranular cracking.

Fracture features at region G are shown in Figure 32.At this point, failure was primarily by ductile dimp-ling.

These features indicate that failure occured in abrittle manner, initiating at three points, regionsA,D, and F of Figure 21. Failure may have initiatedat all three of these locations with the same impactload, or, several separate loads may have been appliedto cause final failure. No evidence of fatigue crack-ing, stress corrosion, or any other slowly progressivetype of failure could be found.

11 . Meta 11ography on Cross Section of Fracture.

After scanning electron microscopy was completed, the ifracture surface was sectioned along the diameter.Figures 33 and 34 show the structure at the cracksurface in the root of the thread at region D ofFigure 21.

Figure 35 shows the crack surface at higher magnifi-cation, approximately 1/8" from the thread root. Notethat cracking is primarily transgranular (arrow 1).Some secondary cracking is evident along the grain ;boundaries at the interfaces of the pearlite and ferrite '

grains (arrow 2).i

|

.-

. .

.

~

. September 9, 1989

REPORT NO. 78429

Page 8.

III. TESTS AND RESULTS: (Continued)

I. St:perficial liardness Testing Nea r Fra :ture.

Rockwell superficial 30N hardness readings weretaken on the polished cross section approxiiaately1/16" from the crack surface. Rockwell 30N readingsranged from 78.0 to 80.0. These readings convert toRockwell B93.0 to 96.0. While slightly higher thanthe Rockwell B89.5 to 91.2 readings obtained on theshank section, they are within the range of accuracyexpected for hardness conversions from the superficialscale.

No evidence of carburization, corrosion, pitting, or.other surface damage could be found near the crach-origin or in the roots of the adjacent threads.

Respectfully submitted,

##TECilNIh!ET CORPORATION

G J= 3e

_, ,

eA. Y.*y ,N Tdo U S 1. ' r.n~ '52Til0h1AS L. PROFT , P .E. L PROFT

5 31.gtWAu.c:

$@15/09Vice-President.-o ( a,

TLP/mP Nn /- .*t.Attachments g_

n,u,,,o

. _ _ _ _ . . __ . _ _ .- - . - . . __ _ ___ _ _ _ _ _ _ _ - _ _ _ _ -

T)(a0 WSeptember 9, 1980-

ag4"9 h- -REPORT NO. 78429

.pyynny:pywp@;;my q m .' ay.m%,sg3w|"g. S ~ '. .+A .b, %. - Yv@& g* , n 7. . e, q ,.,3 ; ;;.y v. ya y,,, 4.n M @;x s{ M w, y y ;-@ P0 cm + , m

,,M. . A, q N ~, 1 ,.,

g;-c,

h m ~ua;J:- --

+ ~jg g.& pu+ g.

$p . b. *'q z. >: .t. . >; mr. . w :s -7g ..

+3...., - ,'

- *.,-g3'*u+.,,.- . e, / M . _ Js- v[ ye. / 4.G. ,

Q|di.M C4'q. , A ?A.'JcM."'%, , ' ^ ;_d ' ,' ~ ' i* %,/ 'M - \[n. , .( 'N-.I.,W .a*1q w j Q -+ ' g&pQ c( gQ3' -Q ' :-m.p_:,.g;X.[:S - -

3 >%:7 .U:; ~ ' ~n

. . ..- . -g.,y

gc; %y w;x. :7.%-

v ..- .v .cp, ap : -: +

, %, a , ; W * . , . . . -x; ..,

r:-e.'-,-< 2''3+5W-_Q,'' ' U_| ,7 g ';g f. h,,4 :

* S*',,e'S". J6.,, x. , ~;~ ,, ... . . .

? . 3 = i, 'g . , ,_ , ;, e -. ,>, * ,( w.:

-

,

'.,

-;

___ _ _ ___ - ._ _ _

. . . ,

{ k'

September 9, 1980 D'

REPORT NO. 78429'

i

i

W:m 7qry:*-7my'-R R+2PQ9i,Y.j:\ty:7.Gi"N q"}** \:;*;'W" :.7 .-r wyW:q=-t _ _ gj

"

h s. y - U lgjIl -t'E f,a ; , .,j g .

-

.,c y eg , . . 1y.. ,' _ l-" h .5& :- s AN N ~ ! Q~|^ ... ,.- >. 2 .$ i X ,;|y' . f*;- L7 |''

'.

gg:: +,jpiga: ~'~W, e , -~: ,, .,m - w #,- 5 , ,. %, . m.- cup -r ; . , . . . _- w , ;,

X. . we

m _ 1M ;WM %4M % W iW ' w ~ , G

dp ~ Q:

. f: U $ Q y.'a, 8 N p?p; f 3;u_ - >. , J g:>p'

#

.:W r.; w,:b &;9h;-(f! - . *

:*

"* *2 '_ QQ ,)_ s --g,. y s '7:- '' + . ..g.wg

J

p|,'74 })9:ayf. %3:"I? .*{|' y:p - . WM SQ, . - - . TV 4i . ' - q:

sm A_,3qgy_..s.yr ...n - ?Y.* : . I.'Q. h Q::4j ,?$L' , q- i

f ',' . ..'a ' {~.,,)5f

'

'

9. 'ar , :' 4 -Q'

j ~- f\v 'tp_ . '- ' u .

m.

: ,As. .n,$'S l' 7' , ) W' ' - i tf ;p _ ? $ * tiv > ~ ' r . g s-m

' ~ - -. - -

*n

k%m ,,Wia, , :,, Np'

.-|.j' :Q% ,,fy% 4 GM '

Q-hfj,pe{i:; h (;. . :, -

a. a.ny: 'w - Aw.s .v:< : '- U',vf7 _._

Y'"e l ; -.

*[, ' J -E ,) C',y

Fig. 4 - Same as Figure 3, at slightly higher magnification.Arrows indicate suspected origins of cracking at

,

roots of thread.

__ . . _ . _ _ _ .._ _ _ _. _ . . _ . _ _ . _ _ _ . - _ _ _ _ _ _ _ . _ _ _ _ .

__. _ _ .

,

i

September 9, 1980 D*-B gg@iM;@lWMU'.

g]iREPORT NO. 78429

" , -,

-: ~ , c mv?)F '9 ~ - , 4 v mq p. , - .y3e n:- e. _ .. y . ' , ,, ,.r.

- ". % :, x

_ ,4 . * : *#, -.''4r| S _'

.

~ % +s... . ,p ,e . x'; ., ,

,;; _.

.ys;-w. ,, .- 6 g t .._:... . .; .,a z'a; g ;z_

m,' o >-t. , s 4 y,p . -. ,. ,w c.., a = m.I

D.

~

, , ..;s

(. r . - , ,- g ;,,

i! ;& 1; <_ .r.

h , -:c''

dy., .p ..:

'

. > v.-

?"

tc , Q*

,

,

r: > -.

_ \_<

.'4.,.-

.\v:r - r ay > .g 5,7

~.-

,

,.d * f _ - ;,_w |

'hT is,

,

,

{-

- a y(.e '

. a uu ? '

Fig. 5 - Close-up view of fracture face as received. Arrowindicates location of EDAX analysis of corrosionproducts. ,

,

; - er' ' ^^~,, . . , ), m

- -.,'

f' | .5,5_

r . ; . ;*- ~ ? & Nh ' ,

$â?. .,.g[jpg ;,,''',sW * *s. ?: /q * QT *,r. , y; ^[ . g ,s.{-A s , a ' *

. .. . ,s.>

..I,%. . .. , s, - 4 s ,. - . - . '

>. . t.e,- ,.

$, . - {,'

,,,s 1- - . ..f. ,.f F . s are , : 1 - 1.w ;

-t

,

- , , ;, ,

. s - ,-

; $ - . .~ p

-

~

4 a -;

t%. 7b , .pk / '

9 .t-; s t;, . k1

e +g,o &'^54 Lg' v.,. , , <

d'y x ,: . r; . .. 4 .'

? f *. ys[. h.+fg.;b .; .,t

| ' ,.b?,.,.t ..~ . ,

w ng s a>9 j;. E.g :[ ' } .

1|

| 1-

1

-

september 9, 1980

| REPORT NO. 78429|

|

.

k.W:.. f

4?I .tp :|, ,

% .- ;y ( -{y.e;'|WN ' y*f'

m +|Q,7 ~ nN,

__ __ _ _ _ _ _ _ _ _ _ _ -

.

phM)ppn Q'J=prf,September 9, 1980

qD jdJLdj,REPORT NO. 78429 ' .11,

' 'I .* ). ~ .M"" 4

g 'w% . . . . . . ' .-j ,i""l',''*- [ (''''.M g Y MN -% * -[ I,I -

s-

! | |.' f ra;- [ ; " '.fbff ^,

eA ~ u e

$ ;_ i' g%..;n>M.,; v-f;. ; , ' ,<' ' ';@v d,p

' '46 .

% w f3:. , 3 ,, J.-

' ' , f ; .):. 'c,-y> J q .:c: ga g , ,,,s+.. ,e awy;r. gg[y n.: 93;3 ~; .q;h;.h5:s,g ih ' -% m(;h fif tg s , M M;@

'

& EV .. : . .'.

@( '~'fgSpn

M ^ J Od V. '.4:>g.t; ;=1

y, ,t n h;wy.. > #yt|:s, .me.m. r y_, ._ ? .n

g.s .y . . ;xg- ""{, h ' M h N 5.IV

. fhjkj k' . M C 5 - e .n fM - - n -q,. ,,cr, pg ,. #,n . _

-w. ,;. .

. c ~4n, w. : :,wc., r % s

,;

.p - .x. .y . c.,. y . .,f.

-

,my o, ..?og - , s: s:v., es , u g,. 4-- ~. _ e ~ a.--; w :. ,. +z. >

- , , . . ,7:. , ,-..+:gr s , ,

,

nt

- ,

{: .: e g-;.:2 m, m . .qm

.. . ....

.. a w. . . . .G.-wax.J s,wa.wa wn Liauk;dOMisdaiD,

.

i

Fig. 9 - Sections removed from failed stud for metallography, !|hardness testing, chemical analysis, and scanning

electron microscopy.i,

.qTpg 7d

. . qi ' r

4c }.. :.. .<

.< 4.) g .5* . q,e..., .* .

N '.W..|. ,% y .[. Q d4fli '' |- '4 '..

. .- J ..,& &y(g2p% .A"' - qm u.. .;. ,

Ag ._ N,,

y..~. t.' $; 4 m- y..,, .,

',. -. .

y P*f. .,m -' ?: - ._'~ ) :e,

; s' g. ' A . ',( ,y,,kag

,

e

7' . ,, 9 ; c. M,+ .. h. QN Y .?' . ..p s'

A. ,-

3 .

Q p , ' 'yQ' *, v . .

. _ . s. ,

,..

s.,./,,

..

,,. z ., .,

. . .. -

.. ... .

,,|,

,

i*

Fig. 10 - Electron image of region shown at arrow in Figure 5.Arrow in this Figure indicates corrosion productshown at higher magnification in Figure 11. (SEM 14X)

|

|

. , , . _ . . ~ _ , , - . . . . _ , . _ _ . - _ , . . . . - - _ . _ _ _ - _ . , _ _ . . _ _ . _ . . . . . _ _ - _ _ _ _ _ _ _ , . , . . . . _ _ , . . _ . . . . - . _ . . _

.

:

a

f September 9, 1980 .

REPORT NO. 78429 !D Q}

;

i

e- - - - , ,_ - . .

, , . y di'~''

* -..:- .y .,y -_

: . s.-.' .h ' ,

,

Y.

' m~3 ,.'

., .t

y- fg,

~d (i .'.M . ,; I'.,

|4! . _ c ._ d '.

Fig. 11 - Corrosion product at arrow in Figure 10. White |-

appearance is due to electron charging, a result jof the corrosion products' non-conductivity. EDAX ianalysis of this r.rea is detailed in Figure 12. (SEM 50X)

; -1 ENTP :: EOLT FRAC S-2 |'

.7 ZAF V=21.5 !=35.0 T=26.6ELEr1 LINE STD iAL K Q=100.OSI KP K ;-

K

CL KV K |CA K |FE K <

|] +&++++++++9. 262 ";AL

j 38.716 ";SI'

.521 *P.

. 47 ? *:S

.410 :CL;I 1.093 *sK

29.411 %CA21.110 *-;FE

i ->0 END'

| Fig. 12 - EDAX analysis of corrosion product shown in Figure 11.I

l

l

!

l

_ _ - _ _ - _ _ _ . _ _ - - _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ . . _ _ _ _ . , _ _ _ _ _ _ . . . _ _ _ , . _ _ . _ _ . _ . _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ -1

j' '\Il U*[D '@hdbSeptember 9, 1980 D* D

*

* LB' ~E* JuREPORT NO. 78429

- .m

-. T ,,

s,

j )

il

|

'

|i

I'

L.~

' .

|

Fig. 13 - Higher magnification view of insulation fiber seenin lower left of Figure 11. (SEM 500X)

I

l

1

-)1 EriTR :: BOLT FPC S-3'-:2 7 ZAF V=21.5 S=35.0 T=26.6ELEM LIfiE STO |

MG K O=100.0 |,

'

AL K j

SI KK KS KCA K ,

!Mri KFE K++++++++++

9.137 *:MG9.325 *:AL

31.052 *:SI.615 %K

1.038 %S22.104 *:C A

1 .577 *:Mri| :'6.14 8 * FE.

-> 0 EriD

Fig. 14 - EDAX analysis of fiber shown in Figure 13.

__.._ ___ _.___._ _ ________.._..___.__._.________.__. _ _ _ _ _ _ _ . _ _ _ _ . _ _ _ - _ _ _ _ _ _ _ . . _ . . _ _ _ .

_ --

,

|.

September 9, 1980 0

REPORT NO. 78429

,'- ,, . w ., .-'-'',' f .'8

gf . ,*

'

ge. f - 1; . .;q p ,,i'' |{'W f Q;- *E

~

. ,.

.u,

.

- /;. T# e f '

o. wS u

..| *. s.

" .'' ' .[] ' " " , j.[{ * , hh. 4#

,

~43 is .itf ; i, ;r.- a a 16. .,-,

-

7:$[,. ..

j- ?- ~ 4: >4 . . ., y i.s.

., j' k * |y$..'" 'j- *Nh

w . ;w e

8 j [. (; .-,

Fig. 15 - Electron image of corrosion on fracture surface,typical of entire fracture area. (SEM 500X)

->1 EriTP :: BOLT FRAC S-4I->7 ZAF s/= 21. 5 5=35.O T=26. 6

ELEt1 LIr1E STDAL K O=100.OT15 KSI KS K

CL KCA Kt1il VFE K++++++++++

1.102 * SAL. 3 05 ";t16

5.909 *;TI.115 ";S

.111 %CL1. 218 * C A1.084 *s Mil

88.153 '0 Er4D

Fig. 16 - EDAX analysis of area shown in Figure 15.

|1

- _. - - - - --- - . _ _ - ._- - - , - - . . - -- .,.. , . . ,- , , . ,, , .--,--,n,,- . , .. . , ,,e,,, . _ , ,

.

September 9, 1980..R,u d37

n-

f*d@V'U MnW:D']f0gdA'

* -

REPORT NO. 78429 a

' ~

yyrmmryyy :nv m q" y}p:M. q . g 'g *- .y

f .;x tjo 4 )y 3c y g[,.;~h:,V & ad:

(n;ggySdQ f'y _,Q - s , -t ; 4: ' 7 ,. , , ~p-,.. n..Ag.-

- y .I . .4,.

k(*w; ; , j- %f- *> a, ,

o.k$[I.I [w'd[?, #5.% W gs ".''; u .; (kJ % Q- o . Y,.,n .

L @'

'; ,-cg 9 4 ;u

Wee.mg: . c q m% ; p-

W V .,, A. . .T L.w ..z . , ., y ;e 5p2. - , .,; -, ,. u.. .-.;.a, . .c m - .,gg - . . .. e*f ; .

(w;QY, |k; |& y,,j%e%j|x' ' o: *. R=? p e ,),.p : x&%.

.

: m s i. : w: n z.. :,n .'

.? L:vzo m >? -

Lyy p+ g::< nw c, r - ; - y;. v. Tyt u . .'f _ ;.'N-?f4: a

_ g| ' f. .'I ','p * ; **'y - -q:e - ~ 5.|, .g ,u ,r y v; 6, n : ,* ; ..wqn .n ? n. n y. bO _

> L >* >Av ;. >.

ove%y QQ g,.ge..e 4a4 + g.p. ./.: 1 w.'.. ~. ,.(g*bd , ;,,:-

_

,.

ff_h&_t*h!,4{ . ,M's & $* .s-|?3; , .e -

& .$Y Q $. f is:.'; % % F s _Y M ; y T ,..* ~,.:. ; : 4 . ~.,

..

- y p:.-=,- ,: Q +. ,y , ny y - n_ 1; . pn.y 7.

m, ,_ _ Q , ,; . :-

.c .c

4 .y;L / m: . . ,:79 y' y,1;. 4,

""

1 y .; c .., .,s - ,A... .- .~. as,; ,m ,. . . u t -M,gk.nW -.. p.

.. e 't AgzMmQ+ei;%d;%y f*;;Q

.

&%.nniuk Z: ^ st3udL% 2 2r d 1 w. ig . 17 - Transverse section through bolt shank. Structure

consists of ferrite with small areas of pearlite atthe ferrite grain boundaries. Roundish grey areasare manganese sulfide inclusions. (200X)

x v. - .. m -.=,7,.,4 -/ - , m,e-m. ;,,,..g;. . g ,- my e,

. . .

, ,K9 [mun - %.q gg=.

N

p'ntg. h. u. m.,3%,. . s .

- )::' '' 5 QeQygW emj' u2. ..w. , - - ., , , . . , .

' * * " ?'* i%. *;w* ' .

*[ , . 7. .a*** k# **",.p q.'"*, ..s

bYWf,hh%*%wyn:w;m. m ; c f ~r/ $d '''%xW | .%sm- ' *

x A.p-.

. .-

{m;m;,We ; ; , . a*. . , m . m . . . . ,, . . ...a

m F,.ce'. ' %. j i en, :. , s. .q :i .,

>.

,:*====--m===*v''.--...-

g| ,>'; -

.s .

.,d,- -* .c- . . . a ,-( . ..N ._ a

%(n& Ann:% w.c: t M* w. e ? &% Q v s. m y w.: . : r.w * v.+ .Muu.s.-A:nw ww,WSQ;- s- -m .; ..R d@h'' %. "Wi:=% s f;; n%R:& W{ %W M%:yh M|&$Q?Q'ffcM f M~ W .?hy%Q%p5k 4WS6hkhd$bbNbdb

Fig. 18 - Longitudinal section through bolt shank. Magnitudeof manganese sulfide (a rrow) is evident in thislongitudinal section. Structure is typical of a lowcarbon, resulfurized, rephosphorized, cold drawnmaterial. (200X)

__ _ _ _ _ . _ _ _ _ _ . _ . _ _ _ _ _ __ ____ - - _ . _ _ ___ _ ___ _ _ __ .._ _

;

September 9, 1980W Wmn

[h l[I$uuuh&,' On*

h .!- D i! -Qu UjREPORT NO. 78429 .

-

1Kyp'g%yggg|F.%9;;ygiggy;gg.qgg ,x"qtwC fy< WMw; ; + w : x.

_ _ _ _ - _ . _ - _ _ - _ _ _ _ _ _ _ _

Il

I

,c.qn[np[n ]i

ig!(LD iSqrtember 9, 1980 !

*

D._

REPORT NO. 784291

7- 4 y.;n >- s-s;.> .g

e]%.?. c. ,

M(4._ 00. e

Y'

4-

..

, , . _

| t:-

.h.f,jj;(Y

,

?'' y_ ,

'-..

. as 1.Pfi~[ . >7g'?r .w3'

i ,,

c;~y , h&-

:d- EinkidS$sb. ;

..

.. -1

Fig. 21 - Fracture surface of bolt after phosphoric acid and ,ultrasonic cleaning. Letters refer to regions examined !,by scanning electron microscopy.

wr;*mLygj;;y; yrY[ * m;'~

?

I }b h Q[Qi4 * 6ishft'I.k. 2t .

.,

! - 2% " ~,

669% fJuh ?;9'gyf.$?.. sg : e ;yh.y;;~U,b '

' c

, z.M

Q)fpf4);Wjt .; s-2 4

Qa.My;b% ,%=rif%N|W);N tf g;-g . g.;

O ~ Tk ;.jn'.s'= n :ti g5 * ;}sc, pg ,2

ig#2;;'r.;x

f h)?)rg (( "6,m a ,nr

V A-L $$

e , ..

Fig. 22 - Electron image of region A. Note secondary cracking atarrow 1. This region appears to be a crack origin, withcracking starting at the root near arrow 1, progressingapproximately 1/8" into the bolt before forming a shearstep at arrow 2 to join the main fracture surface.(SE>l 17X)

_ _ _ _ _ - _ _ _ _ _ _ _ _ __ - _ _ _ _ _ __. ._ _ - . _ _ . -- -_

|*i

September 9, 1980., -

~ .6* .!

gn:, .x z,t

W\ ,,.. m.g v. .g

e

N$..-~

.cs

'.G

. _ . . . _ _ _ _ _ - - _ _ _ _ - _ . __ _ _- - - _ _- _ - _ _ -

|

4

- September 9, I'80 i l,

REPORT NO. 78429

'

_

-. . .-_

I*s.

I t.,

~

'" ;' .

. Tit . ': 1:c'

; q. - ,

2N? $ '

T.|MO|?%M

A (; 9 -

. 2

Fig. 25 - Fracture features at region B. Again, fracture isprimarily by transgranular cleavage. (SEM 1000X)

. . . . _ . , . ,

- ,

:

e -

'e \,

.=

:

_ _ _ - _ _ - _ _ _ _ _ _ _

.

- fj)f?';jj!(3;an '-m

|

g (h{};,!!\ihDJJU L g' "i" Spptember 9, 1980 i. ,

O ,tg ( g" ' ' 'REPORT NO. 78429 >i

. . _ _ _ ,.

* M:}U ~".** .. ' .

E| g,,a,, -- ~ $ ;vs- w a-; ;;. :p. 24h- y.v; w%

YNDiljNNb % ;;.,p. ; .9.~yK ,

.d p %,M. . . .

4 *. , .

9.v3.^ ^

..t

. 3

f '4J

. _,14- - -. h! s c.%2 ; "C. 1 iMb

m .. . ., .y

a> ;. ~.y - nv ,' = t.O y;g.|4

,

Fig. 27 - Low magnification image of region D. Macroscopicfeatures indicate this was the primary origin of'

failure. (SEM 100X)|

-.- -,

8./ .(.% '[

- 'f .% .-3.. ; ft ;. 5 ;*

' ?"*~. J .

'% f.,,

.$ 9-e a,.s ,

r" .( .,s . ,,.

.. / , %

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ .

.

mrrnSe,Ptember 9, 1980 hp m, 1,M R14e h}Ng\1 bifM.EJ!!U\T6S,2*

Jil',,

REPORT NO. 78429

Si .il'

'

_ ,. .s ' . ..

'

i

y,;ijgjktN[Sfit "1September 9, 1980, . ;. _ _ , ga' * DREPORT NO. 78429

by '$G~ ~ g .!';*. . F}',.s -n .~.

s-. y gr.< d

e.h 8'-. s , a3 -,. ,"s p 7- 'k , #

'u

,

, ..

) !,

, ' {1 f^

;*

.

-

u y.

..

x ,r,>'

,e .

,

Jf*

t $~

c ,-.. , . y,e 1 ,.. 1

' '~

''t,

; y{ .;,,

-y cr : ,.. ,} V

,pf | j . .l |

I'.

i- ' h. - [j. . ~ ~

y, .

1,.

Fig. 31 Fracture features in area F. Fracture is again bytransgranular cleavage, with secondary intergranularcracking. (SEM 1000X)

i

^

%~;~.. g? ?hb . *.,e .N . . - . . *' f rr .,e . .- , _, ' -

%. -"#

,(&,;( .. . .Y

.[[. k M-

, wh ' 3,.

. .

g u|4'~" .*

. . _ _ _ . __ _ . _ _ _ _ _ _ . . _ _ . _ ..

<

p 5. @Iv.q k .n\0[N E*

. . Sqptember 9, 1980,7- 0 f l0 . > 'c'hU\g M:

' 1 J L 'REPORT NO. 78429\'

- ~;~: wu.n.,w.n.&v . . .,p ;tq, +:,ug w ,. .

o, w% .,..a :. n. % w,m.

s. r.. m. ..;.< &.. .. ai.

,.. _. : e. n.n .; :m.m :t c:,- , 4 . r .c. .-1. .a.

,- ; ,.'c,. p . . ;.? . . ~ + , ~.,--...,.m..~ _ ,. m,. m. . < ,44;>$. k , * . ee. g -. ., ., ,- . ,,- - . , . a-~ ., . ,x- . .; .. , .?

'4.

,-- , . , ,, - ,. p ~ n v,,.-C.N*-*'*."g',,,"w

7 .. i , .. **

.' t

.

,m.. .. w. r . , .. - . . - ..y

.

.-r -- zr.,. 1: p n. o..p. .

. .

L.- .. , . ... . . . , , .; :; 4 '. . .; ** .. ' n..m .w.. ) ]'. ' , , . ,. ,Q,.: * *K--- . .y, m_.,-) ,. ,,9i, ? :,

.

. m .,.; ..:.. n .. , w . n . s. %|

. ,7n.r. . ; . . ..-. . . .i m ... . , p g ; .. .. ,.

.A .

'nyr|- . ,w .;.. ..

=.-u ,,. . .

,

- . g . ~. , . .u . ... . ,.-; J. - . ~ - . . ..

, . . ,. .

v . _,< w .w. ._. ~, ; . ,. ._ .y . . , . . t . ~;. . , %. m. . ,., s , :

,,9. w.h .>, .: , 2,3. ~% >. m. & x,..~- g + % 4 O : n.

.s, . w u .. . . w .w.g s y

k:h . b ry ,,;

$ f'|. _m.w g.ma m ,w a m,

, . m. ..i

Fig. 33 - Photomicrograph taken on cross section through |fracture surface at location D. Arrow indicates

; origin of crack at thread root. (50X).t.1

4

.y:.;.; g e ny ' >. . , % : 2. . n .. . ,;.. ;- ~... p.,1,> .. .

. y. .

.. . , n ,. w. ..,yf#i.. , . .: ~-' .,. e. i. q .,.u , y :4 .. , w j .-ns - - : . . ~. gs m. p nf. s ? .,,.. c m.

.

s m,..

4 y .~ 4..w q45% =+ i . . %.

> ,

%., :. ...A . ;. - . 4r . .... ' .Y '. - ? . , *" ~':.':. Nfi.h ._ . .: - .' . , A..,

,.

s ,-W e -:- ~~~ r qv

.

:..-, .. . - w. - m . . ; , s. %~. .,. : m. . .i,-. ,: . g

_ , . g . 2.,e J.,;. r. g: :,:2,.; ,.1

^x : : ,: ' .;,- w. ., . .g-

'

[.

' .

3, -. _

,.. . . ;,... > . s;e.o. ;; .:; .e..;. o;.a I.+ ,7.-m .'* ' ,_ . _ _3.;:, y . .'- .,

-' q-,

.a. ~ ~> v$. ,. . ! v.m.em . b , m 4., R ., ' +

c u c .nm am - e n.Rh a4 __ -. --w a we. . . ., .

- m.

'Ipr:4

. g .< m. s . .- : . . - .n,

-

4,i< '. - ;:# *.J W i: i M N3 w ;A&{. , ..,,.4

-

. r ..c c . = = .:. 7 ,s , w.m.m, ..

W & p.: w,*4 &., ,;;*' p,w: f.+ g e Ga*: $W f' ,'.4

-

Q, . . : '. y._;~-.. ,,.-

,e mn..% % %m. :: - g - m . . ~ * i ~J

.

*

.. September 9, 1980 - ,- n,

.h .k-

iREPORT NO. 78429

|

<

t. -v4 % ~/ v3..

. .- ,;

| ,..

- :,*' % -4. , A .''] g. ~;, ,

,: .' 8 %Yr.

4..

..| . >''_ . - - \ ._

, <<

4 s; -e - ,

# 4"2 s,**

,,

y - i. ' (, * . .,, ,-f y W-,

,.

s.-_, .

g+. ,,. . ~. .;e _

*

~(d .- :- w.. : V.u. :-; ' .

c.' ,;N3 , ; .- > y e.s.: ''E~ ~.i . .,sQ # ~70

, .&..M ,cfs !i -' 47 . 30. . .. . ', .-

|:Rakkauxm&d '%se;dA,

I Fig. 35 - Higher magnification view of fracture surface. Notefracture is primarily transgranular (arrow 1) withsecondary cracking along pearlite, ferrite grain1boundaries (arrow 2). (200X)

:

|

4

|

i

||

|

,

I

.--.-- - - - , - - - - - - - - - . - - - , - - - - - - - - - - , , , - - . . - . , - . . - . - . . _ _ . .- - - - - - - - - - - - - -_ --- _---