Short notes on different types of welding and their uses and properties.

1. DCSP(Arcwelding):
Usedfor weldingof highthicknessandhighmeltingpointmaterials.
Welddepositionrate isless.
DCRP(ArcWelding):
Usedfor lessthicknessandlowmeltingpointmaterials.
Welddepositionrate ismore.
>>Penetration:DCSP> AC> DCRP
Constantcurrenttype welding: UsedinManual Arc WeldingTechnique.
Constantvoltage type welding: UsedinAutomaticArcWeldingTechnique.
>>Arc BlowhappensinDCarc weldingnotinAC.
ReducingArcBlow:
>> Provide some extramaterial atthe beginningandatthe end of material knownasTab in andTab out.
>> Reduce the intensityof currentatthe beginningandatthe endof w/p.
Material for flux Coating:
>> De-oxidisingelement:graphite,alumina,ferrosilicon,ferro-manganese.
>> Slagformation compound:ironoxide,silicondi-oxide,titaniumoxide,silicaflourandCalcium
fluoride.
>> Arc stabiliser:Sodiumoxide,calciumoxide,potassiumsilicate.
>> Alloyingelements:chromium, nickel,Co,Vanadium.
>> Gas formingcompound:cellulose,calcium carbonate.
TungstenInertGas Welding:
Uses:Weldingof Al,Mg and itsalloyinautomobile,aerospace andchemical industry.
Generallyusedforlessthan5mmthicknessmaterial.
Metal Inert Gas Welding(DropTransfer):
Uses:Weldingof Al,Mg and itsalloyinautomobile,aerospace andchemical industry.
Generallyusedformore than5mm thicknessmaterial.
Current= 150-400A

2. PlasmaArc Welding:
Maximumtemp.= 11000 Celsius,Current=120-150A.
Uses:Weldingof Ti,Ni,Co, Mo and it’salloyinaerospace, jetengine,turbinebladesetc.
Highm/p and highthicknessmaterialcanbe welded.
Penetrationismore andweldingspeedismore.
SubmergedArcWelding( Canbe usedin flatpositiononly):
Current=200-2000A.
Uses:Weldingof highthicknessplate inship building,fabricationof pressure vesselsanddomesticLPG
cylinders.
Penetrationismore andweldingspeedismore.
Gas Welding:
Neutral flame:weldingof lowandmediumcarbonandmildsteel,castiron,aluminiumanditsalloy.
OxidisingFlame:Weldingof Cu,Zn,Brass etc.
CarburizingFlame:Highcarbonsteel,Nickel basedalloy.
Thermite Welding:
Uses:Repairworkshop,railwayrail,weldingof large size plate,brokencasting.
AtomicHydrogenwelding:
Uses:Weldingof tool steel anddie steel,repairworkshop,cuttingtool anddies.4000 celsius.
Ac powersupplyisusedbecause of uniformheatsupply.
SpotWelding:
Current:10000 – 50000A
Cu electrode isuseddue tolowresistance andhighthermal conductivity.
Uses:Lap joiningof twosheetsinautomobile bodiesandrefrigerationbody.
Seamwelding:
Uses:Fabricationof fuel tanks,radiatorsandmufflerusedinradiatorpipes.
weldingspeedismore.
ProjectionWelding:
Uses:Joiningof threadedscrewandnutsto sheetmaterial,fabricationof grillsandmeshes.
More numberof nuggetcan be producedina single cycle.

3. FlashWelding:
Uses:Joiningof objectendtoend whichare made of highC steel,low Csteel,alloyedsteel andAl and
itsalloys( 5-25mm diameteronly)
ElectroslagWelding:
DCRP isused.
Current= 1000A. thickness=50-250mm.
Uses:Joiningof highthicknessobjectedge toedge verticallyinshipbuilding,fabricationof pressframes
and rollingmill stands.
Explosive Welding:
Uses : Claddingof objectstoincrease corrosive resistance,joiningof dissimilarmaterial.
UltrasonicWelding:
Uses:Fabricationof diodesandtriodes,keysetc.
F = 20-60KHz.
Thickness< 1-2mm.HAZ doesn’tappearhere.
Forge Welding:
Uses:Generallyusedinagriculture applicationforjoiningof object.
Accuracy isless.Increasedstrength.
DiffusionWelding:
Accuracy and strengthisveryhigh.
TO maximize oxide formationandtoincrease the surface finishthisprocesswill be carriedoutin
vacuum.
Uses:Fabricationof composite laminates.
ElectronBeamwelding:
Voltage=40 – 120 kV
No oxide isformeddue tovacuumcondition.Penetrationismaximum.Anodeiscalledannularanode.
Uses:Joiningof Titanium,Ba,StainlessSteel,WandColumbium.Inspace craft,aerospace,nuclear
powerplantandmissiles.

4. Laser BeamWelding:
EnergygeneratedislessthanEBW.
Depthof penetrationandweldingspeedishigh.
Uses:joiningof Al,Ti and superAlloysinaerospace andelectronicsindustries.
Brazing/ Soldering:
Fillermaterial islead+tinalloy>> soldering.(<427 Celsius)
Fillermaterial isCualloy( Cu+Zn, Cu + Al,Cu + Ag) >> brazing.(>427 Celsius)
Uses:Joiningof materialstoproduce leakproof jointslike inradiatorbodies,pipesusedinwatersupply.
Joiningof cuttingtool tipsmade upof tungstencarbide(brazewelding).
>> Mildsteel > Cast Iron> Cu > Al (Weldability)