a bit abt welding

welding...is joining two materials together with or without other additional material... many types of welding in the world...arc welding, resistance welding, termite welding, chemical welding and so on.

normally in my field, we are using arc welding and this arc welding consist of so many ways and thecnique but mainly is smaw (shielded metal arc welding), gtaw (gas tungsten arc welding), saw (submerge arc welding), fcaw (flux cored arc welding), mig/mag (metal inert/active gas welding) and so on..

these are types of welding that are usually used and handy..except for saw that need quite a big machine and equipments. others is small generator or inverter like box and a hold torch.

ive been doing some welding qualifications here at site. for most of the time, usually we do mech. test but at site, these machines or equipments are limited. so for some welding like fillets or seals welds, we will weld bettween two materials, cut them, smooth them with fine sand papers and do

chemical etching... chemical etching is to make all the fusion line visible to naked eye and to make sure that both material bond together to make sound welds...means had enough stregth, bond properly both chemically and mechanically, have no defects (cracks, hole or others) and acceptable with visual appearance...

all these requirements have its own criteria and has to follow strict intl law or gov law or client codes..


here is one sample of etched welds photo..u can see the material bonds and the border is a bit black..that is the heat affected zone (haz) area...this area is quite critical area but depends on the material type...if air hardened material, this area we should see carefully but mild steel..usually will have no problem despite some trouble comes from this area reported back in early years of welding.

this weld is a sound weld, but actually not a good ectched photo. should clean and polish more to remove the cutting line and make clean etch. at site with limited tools, im quite satisfied. but if in a lab, this etched surface should be rejected and need more polishing.

so as for site condition and client agreed that this test piece had passed it test and its qualified to be used for welding...and the welding activity started...hehe