weld testing

7/27/2019 WELD Testing

1/58

Soldering&Bra

zing

Advantages

Low

temperature

heatsource

required

Cho

iceofperma

nentortemp

oraryjoint

Diss

imilarmaterialscanbejo

ined

Lesschanceofd

amagingpa

rts

Slow

rateofheating&cooling

Part

sofvaryingthicknesscanbejoined

Easyrealignmen

t

Strengthandperformanceofstru

cturaljointsneed

carefulevaluation


2/58

W

elding

Advan

tages

Mos

tefficientwa

ytojoinmetals

Low

est-costjoiningmethod

Affordslighterweightthrough

betterutilization

ofm

aterials

Join

sallcommercialmetals

Prov

idesdesign

flexibility


3/58

We

ldability

Weldabilityistheea

seofamate

rialora

combin

ationofmate

rialstobeweldedunder

fabricationcondition

sintoaspec

ific,suitably

designedstructure,

andtoperfor

msatisfactorilyin

theinte

ndedservice

Comm

on

Arc

Weld

ing

Processes

ShieldedMetalArcWe

lding(SMAW)

GasT

ungstenArcWelding(GTAW)or,TIG

GasM

etalArcWelding

(GMAW)orMIG/MAG

FluxC

oredArcWelding(FCAW)

Subm

ergedArcWeldin

g(SAW)


4/58

WE

LDABILITYOF

STEELS

Crack

ing&Embrittlementin

SteelWelds

Cracking

HotCracking

HydrogenAssistedCracking

LamellarTearing

ReheatCrackin

g

Emb

rittlement

TemperEmbrittlement

StrainAgeEmbrittlement


5/58

HotCrackin

g

SolidificationCracking

Duringlaststagesof

solidific

ation

LiquationC

racking

DuctilityDi

pCracking

Ductility

0

Caused

bysegregation

ofalloyingelementslike

S,

Petc.

Mnimprovesresistance

tohotcracking

Form

ationof(Fe,

Mn)S

insteadofFeS

Crack


6/58

Prediction

ofHotC

racking

HotC

racking

Se

nsitivity

HCS=

(S+

P+Si/25+

Ni/100)x10

3

3Mn+Cr+

Mo+V

HCS30,

Highrisk


7/58

Hydr

ogenAssisted

Cracking

(

HAC)

Cold/De

layedCracking

Seriousprobleminsteels

Incarbonsteels

HAZismoresusceptible

Inalloysteels

BothHAZandweldmetalar

esusceptible

Req

uirementsforHAC

Sufficientamou

ntofhydrogen(H

D)

Susceptiblemic

rostructure(har

dness)

Martensitic>Bainitic>Ferritic

Presenceofsufficientrestraint

Problemneedscare

fulevaluation

Technologicals

olutionspossible


8/58

M

ethods

ofPrevention

o

fHAC

Byreducinghydrogenlevels

Useo

flowhydrogenelectrodes

Prope

rbakingofelectrodes

Useo

fweldingprocesseswithoutflux

Prehe

ating

Bymodifyingmicros

tructure

Prehe

ating

Varyingweldingparam

eters

Thumb

rule(based

onexperienc

e/experimental

results):

Nopreheatif:

CE

300MP

a

Highstrengthby

Grainrefineme

nt

through

Microalloying

with

Nb,

Ti,

Al,

V,

B

Thermo-

mechanica

l

processing

Lo

wimpuritycontent

Lo

wcarbonconten

t

So

metimesCuadd

ed

to

provide

precipitation

str

engthening

Weldingproblems

Dilutionfromb

ase

metalNb,Ti,Vetc.

Graingrowthin

CGHAZ

SofteninginHAZ

Susceptibleto

HAC

CEandmethodsto

predictpreheat

temperatureareof

limitedvalidity


23/58

STAINLESSSTEELS

SSdefinedasIron-basealloycontaining

>10.5%Cr&1.2mm

Otherverycommonlyused

arcwelding

processesfo

rSS

GTAW,G

MAW,SAW&

FCAW

Optimalfillermetal(FM

)

Does

notoftenclos

elymatchbasemetalcompo

sition

Mostsuccessfulproceduresforonefamily

O

ftenmarkedlydifferentforanotherfamily


25/58


26/58


27/58


28/58

Martensitic

Stainles

sSteels

Fu

llh

ard

nessona

ir-cooling

from~

1000C

So

ftened

by

temperingat

500750C

Maximumtemperingtemperaturereduced

IfNicon

ten

tiss

ignifican

t

Onhigh-temperature

temperingat650750C

Hardnessgenera

lly

drops

to

1hour)necessaryatannealingtem

p.

Todissolve

allphase

Prop

erlyruncon

tinuousfurnaces

Pr

ovidehighheatingrates

Usedforlightw

alltubes&other

thinsections

If

phasepptn.canb

eavoidedduringheating

Longannealsn

otnecessary

Distortionduring

annealingcanbedueto

Ex

tremelylowcreepstrengthofduplexS

Satannealingtem

p.

Rapidcoolingtoavoid

phase


47/58

MajorProble

mwithw

eldingof

Al,Ti&

Zrallo

ys

Problem

Dueto

greataffinityforoxygen

Combineswithoxygeninairtoform

ahighmelting

point

oxideonmetalsurf

ace

Remedy

Oxide

mustbecleaned

frommetalsurfacebeforestart

of

weldin

g

Specia

lproceduresmu

stbeemployed

Useoflargegasno

zzles

Useoftrailingshieldstoshieldface

ofweldpool

Wh

enusingGTAW,

thoriatedtungs

tenelectrodeto

be

use

d

We

ldingmustbedonewithdirectcurrentelectrode

positivewithmatch

ingfillerwire

Jobisnegative

(cathode)

Cathodespots,

formedonw

eldpool,scavenges

theoxidefilm


48/58

ALUMIN

UMALL

OYS

ImportantProperties

High

electricalconductivity

High

strengthto

weightratio

Absenceofatransitiontemperature

Goo

dcorrosionresistance

Types

ofaluminu

malloys

Non

-heattreatab

le

Hea

ttreatable(a

ge-hardenable)


49/58

Non-He

atTreatable

AluminumAll

oys

Getsstrengthfromcoldworking

Importantalloytypes

Comm

erciallypure(>9

8%)Al

Alwith1%Mn

Alwith1,2,3and5%Mg

Alwith2%Mgand1%

Mn

Alwith4,5%Mgand1

%Mn

Al-Mga

lloysoftenuse

dinweldedco

nstruction


50/58

Heat-treatab

le

AluminumAll

oys

Cu,Mg,Zn&Liadded

toAl

Conf

erage-hardeningbehavioraftersuitablehe

at-

treatment

O

nsolutionannealing,quenching&aging

Importantalloytypes

Al-Cu-Mg

Al-Mg-Si

Al-Zn

-Mg

Al-Cu-Mg-Li

Al-Zn-M

galloysareth

emosteasilywelded


51/58

Weld

ingofA

luminu

mAlloys

Mostwidelyusedweld

ingprocess

In

ertgas-shielde

dwelding

Forthinsheet

G

astungsten-ar

cwelding(GTAW)

Forthickersections

G

asmetal-arcwelding(GMA

W)

GMAWprefe

rredoverGTA

Wdueto

Higheffic

iencyofheatu

tilization

Deeperpenetration

Highweld

ingspeed

Narrower

HAZ

Fineporo

sity

Lessdistortion


52/58

Weld

ingofA

luminu

mAlloys

(contd...1

)

Other

weldingprocessesus

ed

Elec

tronbeamw

elding(EBW

)

Advantages

Narrow&deep

penetration

Highdepth/widthratioforwe

ldmetal

Limitsextentofmetallurgicalreactions

Reducesresidu

alstresses&distortion

Lesscontamina

tionofweldpool

Pres

surewelding


53/58

TITANIUMALLOYS

Importantproperties

High

strengthto

weightratio

High

creepstren

gth

High

fracturetou

ghness

Goo

dductility

Excellentcorrosionresistance


54/58

TitaniumAllo

ys

(contd...1

)

ClassificationofTita

niumalloys

Ba

sedonannealedm

icrostructure

Alph

aalloys

Ti-5Al-2.5Sn

Ti-0.2Pd

Nea

rAlphaalloy

s

Ti-8Al-1Mo-1V

Ti-6Al-4Zr-2Mo-2Sn

Alph

a-Betaalloy

s

Ti-6Al-4V

Ti-8Mn

Ti-6Al-6V-2Sn

Beta

alloys

Ti-13V-11Cr-3Al


55/58

Weldingof

Titaniumalloys

Mos

tcommonly

usedproces

ses

G

TAW

G

MAW

PlasmaArcWelding(PAW)

Otherprocesses

used

Diffusionbondin

g

Resistanceweld

ing

Electronwelding

Laserwelding


56/58

Z

IRCON

IUMALLOYS

FeaturesofZirco

niumalloys

Low

neutronabs

orptioncross-section

Usedasstructuralmaterialfor

nuclearreacto

r

Une

qualthermalexpansiond

uetoanisotropic

prop

erties

High

reactivitywithO,N&C

Pres

enceofatransitiontemp

erature


57/58

Zircon

iumAlloys

(

)

CommonZirconium

alloys

Zircaloy-2

Co

ntaining

Sn=1.21.7%

Fe=0.070.20%

Cr=0.050.15%

Ni=0.030.08%

Zircaloy-4

Co

ntaining

Sn=1.21.7%

Fe=0.180.24%

Cr=0.070.13%

Zr-2.5

%Nb


58/58

WeldabilityDemandsFor

Nuclea

rIndustries

eldjo

intrequirements

To

matchpropertiesofbasemetal

To

performequalt

o(orbetterthan

)basemetal

eldingintroducesfea

turesthatdegrademechanical&

orrosionpropertiesof

weldmetal

Planardefects

Hotcracks

,Coldcracks,L

ackofbead

penetratio

n(LOP),Lackof

side-wall

fusion

(LOF),

etc.

Volumetricdefects

Porosities

,Slaginclusions

Ty

pe,nature,

distribution&locatio

nsofdefectsaffect

de

signcriticalweldjointproperties

Creep,

LCF,cr

eep-fatigueinteraction,

fracture

toughness,etc.

weld testing

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