Manufacturing Engineering II lecture 10.pdf

This ppt has detail explanation in welding area. And in the areas of applications.

1. Lecture -10
Welding
By BeleteAmbachew(Msc.)

2. Presentations/session out line
Define welding.
Know the history of welding.
Understand the application and areas of
applications of welding.
Types of joints in welding.
Describe the classifications of welding .
Identify the symbols of welding and .
Know the different types of welding defect.

3. Definitions of Welding
Weldingisamaterialjoiningprocessinwhichtwo
ormorepartsarejoinedtogetherattheircontacting
surfacesbyasuitableapplicationofheatand/or
pressure.
Insomeweldingprocessafillermaterialisadded
tofacilitatecoalescence.
Weldingismostcommonlyassociatedwith
metallicpartsbutforplasticsalsoitisused.
3

4. 4
Welding
Advantage:
1.Providespermanentjoint.
2.Theweldedjointcanbestrongerthantheparentmaterials.
3.Theweldingjointmosteconomicalmethodtojoinintermsof
materialusageandfabricationcosts.
Limitations:
1.ExpensiveinthetermsofLaborcosts(performedmanually).
2.Dangerousbecausetheyinvolvetheuseofhighenergy.
3.Cansufferfromcertainqualitydefectsthataredifficulttodetect.

5. 5
WeldingHistory
ThermitWelding(1903)
CellulosicElectrodes(1918)
ArcStudWelding(1918)
SeamWeldingofTubes(1922)
MechanicalFlashWelderforJoiningRails(1924)
ExtrudedCoatingforMMAWElectrodes(1926)
SubmergedArcWelding(1935)
AirArcGouging(1939)

6. 6
Weldinghistory
InertGasTungstenArc(TIG)Welding(1941)
IronPowderElectrodeswithHighRecovery(1944)
InertGasMetalArc(MIG) Welding(1948)
ElectroSlagWelding(1951)
FluxCoredWirewithCO
2Shielding(1954)
ElectronBeamWelding(1954)
ConstrictedArc(Plasma)forCutting(1955)
FrictionWelding(1956)
PlasmaArcWelding(1957)
ElectroGasWelding(1957)

7. 7
Weldinghistory
ShortCircuitTransferforLowCurrent,Low
VoltageWeldingwithCO
2Shielding(1957)
VacuumDiffusionWelding(1959)
ExplosiveWelding(1960)
LaserBeamWelding(1961)
HighPowerCO
2LaserBeamWelding(1964)
Allwelded‘Liberty'shipsfailurein1942,gavea bigjolt
toapplicationofwelding.However,ithad drawn
attentiontofractureprobleminwelded structures

8. 8
WeldingApplications
GeneralApplications;
Weldingisvastlybeingusedforconstructionoftransport
tankersfortransportingoil,water,milkandfabricationof
weldedtubesandpipes,chains,LPGcylindersandother
items.Steelfurniture,gates,doorsanddoorframes,body
andotherpartsofwhitegoodsitemssuchasrefrigerators,
washingmachines,microwaveovensandmanyother
itemsofgeneralapplicationsarefabricatedbywelding.
PressureVessels
Oneofthefirstmajoruseofweldingwasinthe
fabricationofpressurevessels.Weldingmade
considerableincreasesintheoperatingtemperaturesand
pressurespossibleascomparedtorivetedpressure
vessels.

9. 9
Applicationsarea’s of Welding
BuildingStructures
AircraftandSpacecraft
Railways
Micro-Joining
ElectricalIndustry:
NuclearInstallations
DefenseIndustry
Micro-Joining

10. Typeofweldingjoints
10

11. Typeofweldingjoints
11

12. TypesofWelds
•A:insidesinglefilletcornerjoint
•B:outsidesinglefilletcornerjoint
•C:Doublefilletlapjoint
•D:Doublefilletteejoint
Dashedlinesshowtheoriginalpartedges
12

13. Typesofgroovewelds
oA:Squaregrooveweldoneside
oB:Singlebevelgrooveweld
oC:SingleVgrooveweld
13

14. •D:SingleUgrooveweld
•E:SingleJgrooveweld
•F:DoubleVgrooveweld
Dashedlinesshowtheoriginalpartedges
14
Typesofgroovewelds

15. TypesofWelds
•A:Plugweld
•B:Slotweld
15

16. TypesofWelds
•A:Spotweld
•B:Seamweld
16

17. TypesofWelds
•A:Flangeweld
•B:Surfacewelding
17

18. JointConfiguration
ButtWeld
•1=GrooveFace
•2= RootOpening
•3=GrooveAngle
•4= RootFace
•5=Platethickness
•6=BevelAngle 1
2
3
4
5
6
18

19. JointConfiguration
Partsofabuttweld
WeldFace
WeldRoot
ToeofWeld
bothside
Face or Weld
Reinforcement
19

20. JointConfiguration
•Partsofabuttweld
HeatAffected
Zone(HAZ)
WeldMetal
Cap
GrooveFaces
Root
Base
Metal
20

21. 21
TypesofWeldingProcesses
I.Liquidstateweldingprocesses(Fusion).
II.Solidstateweldingprocesses.
III.Solid/Liquidstatebondingprocesses.
WeldingClassification

22. 22
1.Liquidstateweldingprocesses(Fusion)
Afusionweldingwithnofillerisreferredtoasautogenouslyweld.
Therearetwoinherentproblemswithfusionwelding;
Effectoflocalizedheatingandrapidcoolingonthe
microstructureandpropertiesoftheparentmetals.
Effectofresidualstressesdevelopedintheparentmetalsdueto
restrainedexpansionorcontraction.
Thiseffecttheimpactoffatiguelifeofweldment.
Use heat to melt the base metals. Filler metal Is added.

23. 23
Liquidstateweldingprocesses (Fusion)
Examples
1.ArcWelding(AW).
2.Resistancewelding(RW).
3.OxyfuelWelding(OFW) .
4.Other Processes:
(ElectronbeamweldingandLaserbeamwelding.)

24. 1-Arc Welding(AW)
•Heatingofthemetalswithelectricarc
24

25. 25

26. 26
2-Resistancewelding(RW)
•Usingheatfromelectricresistancetotheflowofacurrent
passingbetweenthefayingsurfaceoftwopartsheld
togetherunderpressure.

27. 27

28. 3-OxyfuelWelding (OFW)
Heatingwithamixtureoxygenandacetylene
(oxyfuelgas).
28

29. 29
II-Solidstateweldingprocesses.
Insolidstateweldingthesurfacestobejoinedarebrought
intocloseproximityby:
1.Heatingthesurfaces withoutcausingmelting and
applyingnormalpressure.
2.Providingrelativemotionbetweenthetwo surfacesand
applyinglightnormalpressure.
3.Applyinghighpressurewithoutheating.
Intheseprocessesthematerialsremaininsolid stateand
weldingisachievedthroughthe applicationofheatand
pressure,orhigh pressureonly(melting,fillers ).

30. 30
Solidstateweldingprocesses
Examples
1.Frictionwelding(FW).
2.Diffusion welding(DFW).
3.Ultrasonicwelding(USW).

31. 1-Frictionwelding(FRW)
Coalescenceisachievedbytheheatof friction
betweentwosurfaces.
31

32. 2-Diffusionwelding (DFW)
Twosurfacesareheldtogetherunderpressureatanelevated
temperatureandthepartscoalescebysolidstatefusion.
32

33. 33
Diffusionwelding(DFW)isasolidstatewelding
processbywhichtwoMetal(whichmaybedissimilar)
canbebondedtogether.Diffusioninvolvesthemigration
ofatomsacrossthejoint,duetoconcentrationgradients.
oThetwomaterialsarepressedtogetheratanelevated
temperatureusuallybetween50and70%oftheMelting
point.
Thepressureisusedtorelievethevoidthatmayoccurdue
tothedifferentsurfacetopographies.

34. 3-Ultrasonic welding(USW)
Moderate pressureis applied betweenthe two parts with ultrasonic
oscillating motion
34

35. Ultrasonicwelding
35

36. 36
III-Solid/Liquidstatebondingprocesses
Intheseprocesses,thebrazemetal,solder,or
anadhesiveisappliedtothejointinliquid
statewhilethematerialstobejoinedremains
inasolidstate,thatis,theydonotmelt.

37. Featuresofafusionweldedjoint
Fusionzone
Weldinterface
Heataffected zone(HAZ)
Unaffectedbasemetal(BM)
37

38. RegionsofaFusionWeld
Fusion zone(FZ)
Weld interface
Heataffectedzone(HAZ)
Unaffectedbasemetal(BM)
BM
38
HAZFZ

39. 39

40. 40

41. WeldingSymbols
•Examples:SingleVButtWeld
1/8
75 deg
1/8 root
opening
75deg
1/8
75deg.grooveangle
41

42. 13 Prof 41
WELDINGSYMBOL
3-10
3-10
Filletweldsideview
10”
Staggeredintermittentfilletweld
3”
(3/8)
(3/8)
3/8”

43. abdelmaboud 42
WELDINGSYMBOL
SingleVGroove
DoubleVGroove
SingleBevelGroove
DoubleBevelGroove

44. GeneralizedWeldingSymbol
FARSIDEDETAILS
ARROWSIDEDETAILS
Fieldweldsymbol
Weldall-aroundfor
pipes, etc.
D=WeldDepth(usuallyequaltoplatethickness)
L1 =WeldLength
L2=Distancebetweencentersforstitchedwelds
The Field WeldSymbolis aguide forinstallation. Shipyardsnormally do not
use it, exceptinmodularconstruction.
Electrode
Material
D L1-L2
D
L1-L2
Weld Geometry

45. WeldingPositions
INCREASINGDIFFICULTY

46. WeldDefects
Undercuts/Overlaps
GrainGrowth;-AwideTwillexistbetweenbasemetal
andHAZ.Preheatingandcoolingmethodswillaffectthe
brittlenessofthemetalinthisregion
Blowholes;-Arecavitiescausedbygasentrapmentduring
thesolidificationoftheweldpuddle.Preventedbyproper
weldtechnique(eventemperatureandspeed)

47. WeldDefects
Inclusions;-Impuritiesorforeignsubstanceswhichare
forcedintotheweldpuddleduringtheweldingprocess.
Hasthesameeffectasacrack.Preventedbyproper
technique/cleanliness.
Segregation;-Conditionwheresomeregionsofthemetal
areenrichedwithanalloyingredientandothersaren’t.Can
bepreventedbyproperheattreatmentandcooling.
Porosity;-Theformationoftinypinholesgeneratedby
atmosphericcontamination.Preventedbykeepinga
protectiveshieldoverthemoltenweldpuddle.

48. 40
CommonDefectsandCauses
Thedepthoftheweldis
lessthan specifications.
ExcessiveheatExcessive
speed.
Theweldmetalisnot
completelyfusedtobase
metalorpassesarenot
completelyfused.
Description
Cause(s)
IncorrectangleIncorrect
manipulationInsufficient
heat
Weld material flows over,
but is not fused withthe
basemetal.
Slowspeed

49. 41
Common Defectsand Causes--cont.
Weld bead does
not extendtothe
desired depth.
Description Cause(s)
Lowheat, Longarc
,Incorrectjointdesign
Smallindentionsin the
surface of the weld
Excessivegasinthe
weldzone.
Moisture
Rust
Dirt
Acceleratedcooling
Smallvoidsthroughout
theweldmaterial.

50. 42
Usually visible cracks on the
surface or throughtheweld
Common Defectsand Causes--cont.
Description Cause(s)
Acceleratedcooling
Constrainedjoint
Smallweldvolume
Cracksinthetransitionzone
betweentheweldandbase
metal.
Induced hydrogen
Incompatibleelectrodeor
wireAcceleratedcooling.
Misshapenand/or
unevenripples
InconstantspeedIncorrect
manipulationIncorrectwelder
settings

51. Applications