Issue 14

Anno IV Numero 14 Ottobre 2010

Rivista Internazionale Ufficiale del Gruppo Italiano Frattura Fondata nel 2007

Editor-in-chief:

Francesco Iacoviello

ISSN 1971-8993

Associate Editor:

Luca Susmel

Editorial Advisory Board:

Alberto Carpinteri Andrea Carpinteri Donato Firrao M. Neil James Gary Marquis Robert O. Ritchie Cetin Morris Sonsino Ramesh Talreja David Taylor

Frattura ed integrità strutturale The International Journal of the Italian Group of Fracture

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copi grità Struttur 2007). E’ un grità Struttur alutazione d sui fenome tturale. La r ici, chimici e grità Struttur uardanti la m onoscenza d ni possono i numeri sp ’invio dei m vono essere viello@unica alie bilingue) n-line si conc ità Strutturale . Trib. di Ca ctober, Janua rità Strutturale ture, and is mote works ructural inte aterials scient rità Struttural n fracture m aviour of co rs may also conferences o bmission ve to be wr as.it. The pa reception w nths from th

ale è la rivista a rivista ope ale riguarda l ell’affidabilità ni di frattura ivista ha un c matematici. ale si prefigg eccanica dell el comporta essere anche eciali conten anoscritti scritti in form s.it. Il lavoro o Inglese. L luderà entro s (Fracture and ssino n. 729 ry, April). encompasse concerned w and research grity assessm ists, physicis e is a mediu echanics and nventional an be accepted d r symposia a itten using a per may be ill be sent wi e date of sub

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3

Fra

ttura ed Integrità

Strutturale, 14

(2010); ISSN

1971-9883

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aro Let attività il pross

tore, in ques svolte dall’IG imo Convegn to editoriale mesi estivi. ofondamente ico Luca Susm rial Advisory B di esperti i anche il com l Review Board sionare in se do revisori es ottolineare c lti nei differ ll’intera com desidera pr ha che da c queste ultime ei primi num GF per l’aiu

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dove sono ntamenti IGF no dal 13 al anizzazione a struttura or te Editor , o V sta: costituit linea scienti oriali. e avrà anzitu articoli (diret nsabilizzare lutamente u nsomma, se edicato a qu r nascere la r , meritano co

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Strutturale

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M. N. James e

t alii, Frattura e

d Integrità Strut

turale, 14 (2010

) 5-16; DOI: 10

.3221/IGF-ESIS.

14.01

T in

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M Sch Dep mja M Sch Es A B bu En ho het for the cir cre wh ass me K E fra

. N. James ool of Marine artment of M mes@plymou . Newby ool of Marine kom Research STRACT . Th t which is a gineering c mogeneous erogeneous m of a genu differing cumstances ep, environ ere welding ociated with tallurgical fa YWORDS . C cture; enviro

Science & E echanical Eng th.ac.uk

ngineering, U ineering, Nel

niversity of Ply son Mandela

mouth, Plym Metropolitan

outh (UK) University, P

ort Elizabeth

(South Africa )

Science & E and Innovati

ngineering, U on Centre, Ro

niversity of Ply sherville, Joha

mouth, Plym nnesburg, Sou

outh (UK) th Africa

n poorly und ance of m a bridge b displaceme d behaviour surface, or terface has ining perfo ce is domin e. The pape eering prac

misinterpre ther materi macrosco e microsco ge can take tual one wh importance racteristics ( gue or fract n the proble rate the role

is paper co determinin omponents and gener and often n ine interfac philosophie where envir mentally-ass is used to j cracking a ctors in me ontinuum nment. ally, the educ ing the beha racked bodie en very powe r engineering isotropic co lexity is also crease in rigo f a crack. d hydrostat racture are f N

nsiders an im g factor in m and struct ally continu on-continu e between m s of desig onmental in isted cracki oin compon nd uses case chanical per mechanics;

portant top any aspect ures must, um aspects um reality o aterial and n have to fluences ha ng, or corro ents, or wh study exam formance o non-continu

ic, and one s of the ser of necessi of applied f material s environme be merged ve a key ro sion), where ere tribology ples drawn f materials. um materia

that is ofte vice perform ty, provide load and tructure an nt, e.g. at a . The in le in determ performan plays a rol from engin

erstood or etals (and o etween the nt, and th . This brid can be a vir particular rmance cha ated by fati r focuses o tice to illust

ted, als). pic, pic, the ere in e.g. ure, ms of

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studies; fatig

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I N

TRODUCTIO

bod ass hom situ An exa the def pla H

istoric analys of unc

ation of mec viour of stru s subject to e rful in advan artefacts. ntinuum, an introduced a ur necessitat Three dime ic (which re undamentall

hanical engin ctures and m xternal load cing our abil The key a d considerab s the applied ed by a mov nsional stres sist plastic d y controlled

eers has had aterials. In p or deformati ity to calcula ssumptions le complexi loading or d e from unidi s states can eformation by inhomog

a strong fo articular, so on fields) an te internal st in solid me ty is introd eformation rectional loa be resolved and promote eneous, non

cus on contin lid mechanic d fracture me resses and str chanics are uced into an field become ding to triaxi into devia fracture) s -isotropic a

uum mechan s (dealing wi chanics (deal ains and to m usually that alysis when s more realis al constraint toric (which tress compo nd non-cont

ics as a tool th the behav ing with crac ake realistic the body more com tic; consider, which occur promote sh nents. As b inuum mate

for iour ked life is a plex for s in ear oth rials

ies) have be essments fo ogeneous, ations arise. alytical comp mple, the in presence o ormation) an sticity and f

5

M.N

. James et alii,

Frattura ed Inte

grità Strutturale

, 14 (2010) 5-1

6; DOI: 10.3221/

IGF-ESIS.14.01

beh Sev pro stre pro An pla sim sca dis me the Th pre Ass gui of Th the def sur of ser Th tem me am cre to onc pos

aviour it mi eral factors cess in which ss concentra mote 3D str other import sticity is very plified. Whe le yielding, m tribution and chanics, dislo concepts of e fundament dicting fract essment of dance for en a component us, in consid fact that the ect populatio face conditio the applied vice cracking is paper will perature. A chanical engi bient temper ep mechanism be properly s e a critical c ition that is d gue crack gr re accurate K elastic mode was noted b siderations, ing crack gro ture (with a cking of stru vides the beg the 20 th centu ese stress and he 1950’s on s governed b ent from th with fracture cimen. The ACK TIP STR he first crack gr in many

ght be antic serve to mitig Poisson’s r tion factors ess states and ant factor is extensive th re plasticity etallurgical size; heat tr cation mech uncertainty, al role of pla ure using a the Integrity gineering crit or structure ering the beh ir macroscop n), the envir n (roughness field (e.g. pr in materials focus on th lthough no neering prac atures is ofte s is time-de cheduled. S rack size is ifficult to in issue worth owth by the circumstanc owth. An in -solutions o l for crack tip y Griffith [4 and that frac wth. This a magnitude e ctures becau inning of a s ry was the an energy stran crack tip str y the first te e crack tip. occurring a stress inten ESS FIELD

ipated that p ate these pe atio is 0.5 an that arises fr increase pla the relative s e design crite is limited frac factors (e.g. eatment and anics and pl statistics and sticity in crac Failure Ana of Structures ical assessme to fracture an aviour of m ic behaviour onment in w , chemical c oportional o is truly a cutt e metallurgi n-metallic m tice is concer n experience pendent and ub-critical cr reached (whi spect) fast fra briefing con presence of a es but under creasing em r improved f stresses can ] in a classi ture occurred pproach expl qual to the v se of the co ound unders alysis of crac ds were bro ess fields [7] rm in a serie This led to d t a critical m sity factor is S IN THE PR

rediction of rturbations; o d this tends t om plastic f stic constrain ize of critica rion is likely ture will dom crystal struc hardness; su asticity theor reliability hav king of met lysis Diagra containing nt of defects d to plastic aterials under reflects their hich they op omposition, r non-propo ing edge inte cal-mechanic aterials are b ned with the d as a sudden the damage acks may gro ch may be e cture occurs sidering con plastic encla pin the cont phasis on m atigue life pr be improved c paper that when the e icitly links cr alue of the c mplexity in tanding of th k tip stress f ught togethe . He recogni s expansion, efining the n aterial cons used in situa ESENCE OF

structural b ne is the fac o promote 2 low. Howev t (the move f l defects at f to be plastic inate and m ture; slip be rface conditi y. Many ana e to be facto allic alloys ha m (FAD), w Defects [1], [e.g. 2]. Th collapse and applied load microscopic erate (temper residual stres rtional multi rface between s interface in oth interest behaviour o and unfore can often be w very slow ither relative in metals at cerns the pe ve surround inuing contr ulti-paramete ediction mod to include i the phenom nergy release ack size, app ritical strain quantifying e driving for ields perform r to lay the f sed that the i through a 1/ umerator in tant value K tions where PLASTICIT

ehaviour wo t that plastic D stress state er, increase rom plane st racture comp collapse of th aterial behav haviour; grai on; residual lytical and n red into the s led to the hich was d and has been e FAD appro plots this stat or deforma composition ature, chemi s state) as we axial loading metallurgy, relation to ing and imp f metals. It seen phenom monitored ly via fatigue ly small in te speeds which rturbations im ing the crack oversy surro r characteris els, brings in nfluences ari enon of ru d by crack ex lied stress an energy relea and measurin ce for crackin ed by Inglis oundations o ntensity of th √r dependen this first stre C appropriat the overall Y

uld generall deformation s, whilst a se in compone ress to plane ared with zo e structure a iour will refle n and phase stress state). umerical app analysis. adoption of eveloped for adopted in ach conjoint e on a failure tion, full con and conditi cal species, c ll as the mo ). The pred materials scie cracking pr ortant, it re is also the c enon, whilst in service allo or environm rms of the s can reach ar posed on t . These pert unding plasti ation of cra to sharper f sing from pla pture in sol tension was d the concep se rate G C ), b g the work g. Other im [5] and West f fracture me e applied str cy where r i ss term (σ√a) e to the par stress-strain

y be difficul is largely a cond is the l nt or structu strain situati nes of local nd the analy ct interaction dimensions This is the r roaches are a two param the CEGB similar Britis ly considers locus diagra sideration ha on (heat trea ontact with o de, frequency iction and u nce and mec oblems in m mains true t ase that failu failure by co wing repair entally-assis cale of the s ound Mach 0 he elastic str urbations are city-induced ck tip stresse ocus the que sticity. ids was gov equal to the t of a materi ut was diffic to fracture. portant work ergaard [6]. chanics in th ess field nea s the distanc to be the ‘ st ticular state constitutive b

t and imprec constant volu ocal reductio ral size tend ons). plasticity. W sis can be gre s between sm ; inclusion t ealm of frac approximate eter approach R6 docum h and Europ the susceptib m. s to be given tment, hardn ther parts), t and comple nderstanding hanics. etals at amb hat the bulk re by crackin rrosion, wea and replacem ted cracking, tructure, or .4 [3]. ess field driv relatively m shielding du s, to give ei stion of whe erned by en energy absor al’s resistanc ult to extend Nonetheles in the early e work by Ir r the tip of c e of the stre ress intensity fa of stress in ehaviour of

ise. me n in s to hen atly all ype, ture and to ent, ean ility to ess, heir xity of ient of g at r or ent but in a ing inor ring ther ther ergy bed e to to s, it part win rack ssed ctor, the the

C R

fati mo the It con dur frac cra pro of Th in t wa elem K ’ spe T

6

M. N. James e re there is a l tical values o by the equat K 2 /(1 – ν 2 )E stress intens associated d Plasticity is pparent crack (perhaps < 0 rate on the en sub-critic – K min . With diction und ) questions ation of phe ould seem li ack tip durin boundary c enclave surr ility-induced ratio ν = 0.5 CJP model rding stress nsity K S . An full-field pho stergaard or nting the CJ ion for 2-term 3 2 Bz z C    1 2     D, while the 3 2 Bz z    D and D+E contact stre ) and a comp his provides erpendicular   ' z  o Eq. 4 to gi 3 2 z z  A (A+B = 0

t alii, Frattura e imited extent f stress inten ion G = K 2 / . ity approach ecoupling of primarily con length), stre .6) of the yie basis that if al crack grow the developm er cyclic load remain as to nomena tha kely to assist g fatigue crac onditions tha ounding the stresses at , whilst in el [12, 14] for intensity K R alysis of its toelastic dat Williams [15] P model is gi s, K and T 0 z

d Integrità Strut of crack tip sity factor an E where E have proven local crack t sidered throu ss state and ld strength o critical crac th under cyc ent of fractu ing has beco why, and ho t explicitly a in resolving k growth [10 t would be crack. Thes the elastic-pl astic deform crack tip str which captu capability in a, indicate a l equations. ven below al stress is:

turale, 14 (2010 plasticity (wh d strain ener is the elastic very useful i ip microstru gh its influe through the s f the alloy. k growth un lic loading m re mechanic me the prim w, an elastic rise from pl a number o , 11]. The ex imposed on e arise from astic interfac ation ν ≈ 0.3 esses leads t res wake con characterisin ower fitting ong with 2-t

) 5-16; DOI: 10 ich arises fro gy release ra modulus of n characteris cture and pla nces on speci tipulation th Paris [8] ext der monoto ay be gover s into a matu e applicatio approach to astic deform f controversi planation ad the applied crack wake c e. Plastic d and plastici o a modified tact influenc g near-tip fri error than eit erm and 4-te

.3221/IGF-ESIS.

14.01

cra stre as pla Lin in c eve (via lev the gov of are inte Ex abl Sat wit wo pla pla con stre driv cra dif T -s Th the

cked body is ss concentra recognised in ne strain this ear elastic fr racked and s nts from the the Irwin pl els should be K concept erned by the the applied st a of fatigue nsity approa tremely inter e to provide isfactory ans h plasticity-in rk on this is stic ‘inclusion sticity-induce stant volum sses must ex ing crack gr ck tip, and a ference in pri tress) or four e stress varia Williams sol Nf h  ere the two u ne. The 4-te Nf h  ere the four u Nf h  ere the four u ck growth K nsity acting stic interface parable with nsidering dis ction is given  2 u   placement fi

linear and ela tion at the cr the case of relationship acture mecha tressed struc bulk applied astic zone co a relatively to fatigue c stress inten ress intensity crack growth ches. esting (and la an adequat wers to these duced shield sue [12-14] c ’ representin d closure) a e process wi ist at the in owth forwar shear-induce ncipal stresse -term solutio nt of the equ ution. The W

stic, i.e. whe ack tip). Cri plane stress becomes G = nics and the tures with an elastic field. rrection to a low fraction rack growth sity factor, th , ΔK = K max and life pre rgely ignored e characteris questions w ing of the cr onsiders the g the plastic nd compatib th Poisson’s terface. The ds K F , a reta d stress inte s [14], using ns to the We ation represe illiams solut fficients are s:     A, B, C and e A, B, C and crack flank k growth K R K S term). T data. elds, both p xy A z  1 2 xy Az      ' z z   ubstituted int   1 2 xy Az    

m the high l te are equival the material. ing critical st sticity contro men complia at nominal st ended the us nic loading ned by the ra re discipline, n area for st crack growt ation proces es [9] associ vanced in re elastic field b ontact (so-ca eformation ty-induced sh stress inten es ahead of nge patterns her two- ( K rm equations

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nknown coe rm solution i

) and C and

z is the coo

tressed poin

t in the com

rdinate of a s

plex

1 2

1 2

( B z z  

0 ) z Cz D   (

i

) z z 

2



  

(2)

y

x

wh

nknowns are 2 y x     nknowns ar F , T -stress, a to retard crac (leading to a photoelastic placement fi by:   iv z   elds can be s i

CJP model i 1 0 2 Cz Dz l   = 0. This m ss with a 1/ atibility-indu fringe pattern and parallel

s given as: 3 2 nz Ez zln   odel allows √r distributio ced shear str s for differe to the crack

z for calculatio n behind th ess as a boun nce in princi face, the M

(3) intensity driv leading to st on at the ela hich are dire i complex st

wh cra inte pla com Co fun

n of a stress e crack tip ( dary conditi pal stresses w uskhelishvil

ing ress stic ctly ress

(4)

Dis

ve:

7

M.N

. James et alii,

Frattura ed Inte

grità Strutturale

, 14 (2010) 5-1

6; DOI: 10.3221/

IGF-ESIS.14.01

   

 iv       2 B E z  

1 2

1

1 2

C Ez lnz 

F z

 2 u    z    Az   

  2 2 B E z 

2 4 Ez  

2

4

4 C F z     

1/2

1/2 Ez ln  

(5)

2 C F z    

1/2

1/2 Dz ln 

1/2 2 z Dz  

wh   u,v   z A, Cas exa K S , fou

ere:

= s = f = h = a = c = u

hear modulu unction of Po orizontal and uxiliary funct omplex coor nknown coe ese terms allo correlation t llows (note t -direction an

s, MPa isson’s ratio vertical disp ions in Musk dinate in the fficients and ws direct co echniques (F hat when usi d T y in y-dire

ν lacements

   , z z  B, C, D, E , F ting the CJP mple, using K R and the T nd as compo

helishvili‘s m plane z=x+iy D+E = 0 mparison wi ig. 1). Expr ng displacem ction):

odel

model in th digital image -stress as fo nents T x in x

th full field c essions can b ent data rath

rack tip disp e directly ob er than stres

lacement fiel tained from s data, the T

ds measured, Eq. 5 giving -stress has to

for K F , be

Figure 1 : full-fiel

Displacement d fitting betwe a crack 29.3

field around a en model and mm long und

crack tip mea experimental er a load of 12

sured using D data. A 2 mm 0 N. The mea

IC techniques thick alumini surement regi

. The pattern um specimen i on is 17.7 mm

of points is us s used which c by 13.2 mm.

ed for the ontains

  



  

1 2

 2 A B 



 

 8 E

K

r

Er l

n r

l im 2 

2

3  











I

y



r

0



(6)











 

 

r  

A B 

K

l im 2





xy

S r

2

0



3

2 

 r  







 

 

3 D E 

K

l    R r

im 2

x

0



C

T T

X

F

 

y

It i pla

s not yet clea sticity-induce

r whether th d growth rat

e CJP mode e perturbatio

l, based on t ns, or lead to

he plastic inc a reconcilia

lusion conce tion of confl

pt, will prov icting views

ide a means of plasticity-i

sing tip

of characteri nduced crack

8

M. N. James e ences of pla astic full-field

t alii, Frattura e sticity that h fringe data.

d Integrità Strut ave, up to no

turale, 14 (2010 w, largely be

) 5-16; DOI: 10 en ignored a

.3221/IGF-ESIS.

14.01

shi fitt

elding. It do ing error whe

es, however, n compared

capture influ with photoel

nd gives a lo

wer

I N

TERGRANU

LAR FATIGU

E

dep dis stru thr Th sam I

plasticity-ind eels with a b n movemen atom conte dislocations is non-planar d asymmetri s to move a on on the sa

ntergranula alloys, e.g. consequen endent on t locations, wh cture of a ½ ee 1 / 6 [1 1 1] is leads to sl e as that req

r faceting du certain α-iron ce of crystal emperature, ich are less [111] screw fractional dis ip asymmetry uired to mov

ring fatigue s and ultra-l structure a strain rate an mobile than dislocation in locations whi whereby th e it in the op

is a second ow carbon st nd dislocatio d interstitial non-screw a bcc alloy ch also sprea e shear stres posite directi

uced phenom ody-centred c t [16]. Slip nt and are g and which m , lying in thr cally on three dislocation i me plane.

enon that o ubic (bcc) cr mechanism overned by ake cross-sl ee {1 1 1} p {1 1 2} plan n one directi

ccurs infrequ ystal structur s in bcc all the behaviou ip more diff lanes (Fig. 2) es in the twi on on a slip

ently in spe e, and is a di oys are stro r of long sc icult. The c . It spreads nning sense plane is not

cific rect ngly rew ore into [18]. the

Figur period

e 2 : Core of a ically repeating The arrows ar crew disloca planes. Int w interstitial s rise to shap long grain b tended crack s subjected t xample of th ed in the au alance severa are likely to bility and dee gen, typically however, l ined above. Mn in solid lower interst steels, desp ng crack init

½[111] screw the three (11 e the relative ( tions hence d erstitial atom atom conten e changes of oundaries w paths plasti o fully revers is phenomen tomotive ind l conflicting be subject t p-drawing c 10-200 wt p ow interstitia IG cracking solution. Su itial C, B or N ite plastic def iation and lo

dislocation pa 1) layers (distin screw) displac epends on st s present in t (e.g. C, B, N bcc grains u hich favours c deformatio ed loading in on occurs in ustry for for requirements o reversed cy apability are a pm (0.001 w l content ( may also be sceptibility t [16]. ormation bei ng life fatig

rallel to the pl guished by di ements of neig ress-assisted the cores of ) would the ndergoing fu the nucleatio n may be str high cycle fa interstitial-fr ming thin ga , i.e. deep-dr clic loading ssisted by ve t % to 0.02 w < 40 ppm) promoted w o brittle frac ng strongly l ue, the fatigu

ane of the figu fferent colour hbouring atom thermally ac screw disloc refore prom lly reversed n of intergr ongly localis tigue where l ee (IF) steels uge sheet b awing capabi in service. T ry low amou t %). At th promotes IG ith high stre ture has bee ocalised at gr e performan

re. The atomic ed atoms) alon s along the disl tivated gener ations appare ote slip asym cyclic deform anular fatigu ed within gra evels of plas which const ody panels. lity, fatigue r he conflict in nts of interst e small plast cracking ngth IF stee n shown to ain boundari ce is little d

block is form g the dislocati ocation line [17] ation of kink ntly make th metry in bcc ation. Stres e cracks. Du in boundarie tic strain rang itute one of t In performa esistance, ten requiremen itial elements ic strains typ through the l grades con be higher in es, which lea ifferent to o

ed by on line. .

1 0} sier slip ons ent y in ups ese and use on, ycle etry sed e of ting able

Th and [19 asy can gro sus An of allo ligh inc bor fati me lev inc In par

e motion of s {1 1 2} slip ] and ultra-lo mmetry give then form a wth along ex ceptible alloy interesting e bcc steels us ys have to b t weight and reased forma on and nitro gue loading, chanism outl els of P and reased P and the case of IF ticularly duri

pairs on {1 is process ea alloys. This s concentrati ring subsequ s, particularl e are low. he major gro nce terms, th sile strength ts arises beca such as carb ical of high c slip asymm taining increa the presenc ds to IG face ther compar

9

M.N

. James et alii,

Frattura ed Inte

grità Strutturale

, 14 (2010) 5-1

6; DOI: 10.3221/

IGF-ESIS.14.01

allo IG to e

ys which do facets on a f ither critical

not exhibit racture surfa or sub-critica

such IG face ce are usually l cracking w

ting during c an indicatio ould be lowe

rack initiatio n that some red. Fig. 3 sh

n and growth form of emb ows typical I

[16]. This rittlement ha G faceting o

is unusual, as s occurred an bserved in th

the presenc d that resista ese alloys.

e of nce

R E

SIDUAL STR

ESSES AND

WELDS

R

esidual consequ of the y

stresses aris ence of man ield or proo es over whic aries with typ , including c e crack grow ts. They als cal phase tra nical propert

e as a conse ufacturing an f strength. h the residu e, nature and hanges to lo th. These st o occur as a nsformation ies, microstru

quence of m d fabrication These region al stresses sel origin [20]. ad eccentricit resses often a consequence s), and are p cture and ge

isfit betwee processes, w s of misfit c f-equilibrate. Type I mac y and failure rise from no of the crack articularly in ometry of th

n various re ith magnitud an occur wi Their influe rostresses can stress durin n-uniform pl growth proc fluenced by e componen

gions [20] an es that local th several di nce on mech affect the p g buckling, a astic deform ess itself (cra thermal proc t or part.

d are hence ly are often a fferent size s anical perfo erformance o nd influence ation or from ck tip plastic esses (e.g. h

an inescap high propor cales and he rmance of al f structures s on the frac assembly m zone and c eat treatmen

able tion nce loys in a ture isfit rack t or

dif the num stre of wa wel

ferent distanc refore also v ber of ways ss and fatigu structural par ke effects, lo ding), mecha

Figure 3 : IG

faceting near t

he crack initiat and 0. hly variable; ominally sim f stress conc ing service ample, peeni onent [23]. ue cracks and . of intermet widespread e lack of accu only used st often has a e ways of de ects. A larg sing low ener n ‘innate’ co e available X s a form of p

ion site in an 013Ti. The st both from p ilar condition entrators suc [21]. Comp ng [22] or co Type II stres corrosion p allic particles xistence and rate 3D info ructural joini deciding influ aling with re e contributio gy X-ray sou ntribution to ray intensity article accele

IF steel contai eel has a yield lace-to-plac s. The exter h as weld toe ressive resid ld-working te ses are interg rocesses. Ty and regions, frequent us rmation on t ng process a ence on the sidual stress n to this un rces, impreci scatter from increased dr rator in whic

ning 0.001C, 0 strength of 17 e within the nal applicatio s, defects and ual stresses chniques, wh ranular in sc pe III stresse and from di e of residual he magnitud nd the resid analysis outc in fracture m certainty ari sion in hole d the welding amatically as h particles (u

.380Mn, 0.004 4 MPa. component, n of cycles o cracks, lead are routine ich are often ale and influ s are of the slocation stre stresses in e e and re-dist ual stress di ome [24]. T echanics ass ses from dat rilling param process [24]. synchrotron sually electro

Si, 0.008P, 0.0

05S, 0.018Nb

Th stru par res per fati suc fro slip cyc loa We ass to eng sur of Fro A s

eir magnitud ctures produ ticularly in th idual stress formance thr gue ‘quality’ h as the initi m interface c processes. lic loading, t d. lding is the essment for w propose very ineering crit face measure measurement m the 1970s ynchrotron l

es can be hig ced under n e presence o profiles dur ough, for ex of the comp ation of fatig oherency, e.g Despite the here is still a most comm elded joints conservativ icality of def ments, e.g. u s, alongside a onwards, th ight source i

and between f load, displ s to significan ly used to considered ence aspects order of atom ss fields, and nhancing per ribution (or r stribution as hus fatigue d essments of a limitations eters and rel light sources ns) are initia

component acement or h t changes in enhance ser as improving of performa ic size and a influence pla formance un elaxation) un sumed in de esign codes t remanent lif associated w atively small were develop lly accelerate

s or eat, the vice the nce rise stic der der fect end e or ith sets ed. d in

10

M. N. James e to a storag light, equiva particle beam tors’’ and ‘‘w ergy into hi 0-400 keV). fast, accurate y, many orde r divergence f source cros ngth

t alii, Frattura e e ring where lent to an en . Third-gen igglers’’) in gh energy ele residual stre rs of magnitu of the beam s section and

d Integrità Strut they are m ergy of 6 G eration synch straight sect ctromagnetic ss measurem de greater th solid angle o

turale, 14 (2010 ade to circu eV) in an e rotron X-ray ions of the radiation (‘h ents through an with conv f emission is

) 5-16; DOI: 10 late via mag lectric field. sources are storage ring ard’ or high up to about entional X-r small

.3221/IGF-ESIS.

14.01

a l acc car mu elec see Syn Its

inear acceler elerated (to efully synchr lti-magnet in tron beam a Fig. 4 – with chrotron rad advantages d  High br  High co  Low em  Wide tu  High br

ator and the about 0.6x t onized with t sertion devi nd convert s energies in t iation is very erive from: ightness and llimation, i.e ittance, i.e. t nability in en illiance (pho

n injected in he speed of he travelling ces (‘‘undula ome of its en he range of 2 suitable for high intensit . small angula he product o ergy/wavele ton flux)

netic fields Both fields designed aro which bend energy X-ra 10 mm of s ays X-ray tub

and are und the ys – teel. es

Fi

gure 4 : Electro

magnetic spe

ctrum showing

the region of

visible light [2

5].

Th loc a ty Ne of par wh em 0.1 spe ma it w dif Ne Pa In un

ese attributes ation ~ 10µm pical experim utron diffrac steel). The r ticularly whe en waves en anating from Å to 1000 Å cies or comp terial. Such a ill scatter u fraction. Neu utrons rticle beam (n teractions wit paired electro attered by all drogen isotop ep penetratio ss intense be

, coupled wit ) capable of ent extendin tion is the ot equired free n fission occ counter an a reactor can , making th lex biopolym neutron bea nder a limite tron and syn eutral subato h the nuclei ns (in the sa elements, als es n depth (bul am measurin

h greatly imp accommoda g over sever her widely u neutrons can urs. All qua array of obs be slowed em an ideal ers. One Å m can then b d number o chrotron dif mic particle) and the magn mple) o the light on k studies of g larger samp

roved data a ting large and al days. sed technique be obtained ntum particl tacles whose down and sel probe of ato ngström (0. e used to pe f well-define fraction tech

nalysis softw heavy comp capable of in a nuclea es can exhib size is com ected by thei mic and mo 1 nm) is the rform a diffr d angles acc niques can pr

are and auto onents, allow yielding data r reactor whe it wave phen parable with r speed such lecular struc typical separ action experi ording to th ovide compl rotron radiatio t beam (elect actions with ample) ly scattered b l penetration intense beam

mated 3D st large sets o through thic re they are s omena such the wavele that their w tures, either ation betwee ment; in imp e same Brag ementary info n romagnetic w the electrons y heavy elem depth (surfa measuring

ages (with pr f strain data k specimens et free throu as diffractio ngth. A be avelength lies in the form n atoms in a inging on a c g's law that rmation: ave) surrounding ents ce studies of small or ultra

ecision of sp to be acquire (up to ≈ 50 gh nuclei de n, which oc am of neutr in a range f of single ato solid crystal rystalline sam describes X

atial d in mm cay, curs ons rom mic line ple -ray

Synch Ligh Inter the s Main Smal Very

etic moment es like the samples) les

of

the nuclei (i

n

Sc hy De Le

samples) -dilute sampl

es

11

M.N

. James et alii,

Frattura ed Inte

grità Strutturale

, 14 (2010) 5-1

6; DOI: 10.3221/

IGF-ESIS.14.01

Ap

plications: Magnetic st Organic stru Bulk studies Low-energy ilar improve lysis for high les for most neutron or s e utility of n ds on the so e-Langevin ding using a ese repair w erimposed o n the parent cesses, simu ss corrosion ss, and it is c these various fraction inten

App  P  F  S  H e

lications: rotein-crysta ast chemical urface studie igh-energy s lectron energ sources, in n and stress -situ loading ows residual SALSA neu erned with a ing with 316 austenitic sta uld be expe g either subm he stainless s tion industry dures will aff at texturing i ent [26].

ructures and ctures using (strains, exc spectroscop ments to th intensity ne metallic alloy ynchrotron i eutron diffra phisticated 6 in Grenoble utogenous fr elds were m n convention plate. The lating the or cracking (SC learly import welds are sh sities, requiri

excitations the H-D iso itations) y, e.g. molecu ose found w utron source s. It is now nstrument. ction is easily -axis hexapo , France. T iction stir we ade in annea al V-prepara original but iginal constru C) during se ant to know own in Fig. ng long coun

l structures reactions s (defects, co pectroscopy y-levels automated data can be o to specimen stresses bein tron diffract ssessing the L and nicke inless steel p cted to displ erged arc o teel tanks. , which is dri ect the residu n austenitic w

   

tope effect lar vibration ith synchrot s, mean that also possibl demonstrat d Stewart pla his experime lding and las led SA240 G tion butt we t welds wer ction metho rvice in the p how repair w 6. It is wor t times for e s

rrosion) , e.g. measure sample posit btained over s whilst they g measured ion instrume influences o l-based powd late 10 mm ay better cor r manual m Stainless stee ven by high al stress dist eld metals c

ments of ioning and a wide rang are mounted in stainless s nt at the Ins f overlay re er consumab thick and w rosion resista etal arc weld l can experie levels of resi ribution. De an lead to w

Sim ana sca the Th wel Lau wel Th sup tha pro stre stre of dif

ron radiation residual strai e to apply in ed; Fig. 5 sh tform of the nt was conc er beam weld rade 304L lds. They wo e made usin ds used in t ower genera elding proce th noting th ach measurem

data e of on teel titut pair les. ere nce ing nce dual tails eak

Figure 5

: Measuremen

t of residual st

resses in 16 m

m thick plates

of 304L stain

less steel.

Figur

e 6 : Illustratio

n of repair we

ld procedures of fusion w

superimposed elds in 304L st

on SCC crack ainless steel.

s in the heat-a

ffected zone (

HAZ)

12

M. N. James e ed using the mm, and a ransverse to spacing of 2 mm and 8 m stir weld) are rections mea rlay sample o . Peak stress e (Fig. 9), wh erefore be g er reduce re

t alii, Frattura e {3 1 1} pla neutron w the weld is mm from the m into the p shown as co sured at a de ccur at abou es in the repa ilst the corr reatly reduce sidual stresse

d Integrità Strut nes in the al avelength o shown in F centre-line late. Residu ntour maps pth of 1 mm t 5 mm to th ir overlay are osion resistan d after this s and these

turale, 14 (2010 loy giving a f 1.5488 Å. ig. 7. of the weld a al stress dat in Fig. 8a, wh below the e side of the lower than t ce of the ov repair proced can be re-me

) 5-16; DOI: 10 diffraction The typica t a depth of a for specim ilst Fig. 8b g surface of t centre-line o hose occurri erlay alloy is ure has bee asured after

.3221/IGF-ESIS.

14.01

Ne ver for Th spa ove stre hig but site 304 trea spe

utron diffra tical and ho measuring e 3D stress s cing of 4 mm rlay weld sup ss profiles in hest tensile r t weld, wher welds made L. The pos tment of the cimen.

ction data w rizontal slit strains in th tate was mea at depths erimposed o the three c esidual stress e the FS weld in the stainl sibility of SC weld region

ere measur sizes of 1.1 e direction t sured with a of 2 mm, 5 n a friction oordinate di es in the ove was located ess steel plat C should th would furth

angle of 91. l sample set 1 mm and wi en 3 (laser b ives the resi he overlay. f the origina ng in the orig higher than n applied. H heat treating

35º, -up th a eam dual The l V inal the eat the

Figure 7 :

Two 304L sta dete

inless steel we rmination of t

lds shown in p he strains tran

osition on the sverse to the w

SALSA instru eld.

ment for

Fig

ure 8a : Residu

al stress conto

ur maps for F

SW and laser b

eam weld ove

rlay on a V-bu

tt weld in 10 m

m plate of 30

4L stainless s

teel.

13

M.N

. James et alii,

Frattura ed Inte

grità Strutturale

, 14 (2010) 5-1

6; DOI: 10.3221/

IGF-ESIS.14.01

Figure 8b :

Residual stres

s profiles at a

depth of 1 mm

below the su

rface of the w

eld overlay.

s clear that n vice welds a bration of th measuring re ice spacing d ion. An im asurements o m a number is brief discu rface betwee ally require nomena.

eutron and s nd other com e accuracy of sidual stresse 0 , which is a portant aspe n toothcomb of relevant p ssion has, h n metallurgy an understa

ynchrotron d ponents, p the predictiv s using diffr ffected by fac ct of diffrac specimens c ositions in th opefully, ind and mechan nding of th

iffraction ar articularly if e model. action techni tors such as tion-based m ut across the e plate. icated that n ics in materi e effect of

e very power the results a ques, crystal composition easurement weld region ot only are als performan crystal struc

ful technique re linked to lattice spacin and micros s is therefor [27] or via u residual stre ce, but also ture and mi

s for assessin finite eleme g is determi tructure and e determina se of small c sses an inter that their me crostructure

g 3D residu nt modellin ned relative t hence can va tion of d 0 , o ubes (perhap esting demo asurement a on continu

al stress field g and used o the strain ry across a w ften by mak s 2x2x2 mm) nstration of nd interpreta um and phy

s in as a free eld ing cut the tion sics

It i ser cali In latt reg me fro Th inte equ phe

Fi

gure 9 : Residu

al stress conto

urs for an orig

inal site weld

made in the 10

mm 304L sta

inless steel pla

te.

14