Gas Tungsten Arc Welding thin sheets of austenitic stainless steel type 304L results in unacceptable distortion. What can be done to improve results?
Compared to carbon steels, austenitic stainless steels have higher thermal expansion and lower thermal conductivity: these are the main reasons contributing to unacceptable distortion. GTAW is a proper process to weld such jobs but, due to the low current employed, manual operation may be difficult to control. Better results could be obtained by mechanized welding. Other precautions include proper fixturing, pulsed current if possible and step welding. Good cleaning and preparation are always important. Constant current, non pulsed power supplies of drooping-voltage characteristic are used with direct current straight polarity, electrode negative. Pulsed current may provide better weld control to avoid burn through. Most widely used tungsten type is that with 2% Thoria (EWTh-2). High frequency should be used to start welding and to avoid contamination due to electrode contact with the weld pool. Argon is used as the shielding gas. The conical electrode tip can be ground with different
