Effect of nitrogen addition to shielding gas on residual stress of stainless steel weldments

The objective of the present study, was to investigate the effect of nitrogen additions to the shielding gels Oil the ferrite content and residual stress in austenitic stainless steels. Autogenous gas tungsten arc (GTA) welding was applied on austenitic stain less steels 304 and 310 to produce a bead on plate weld, The delta ferrite content of the weld metals was measured using a Ferritscope. The residual stress in the weldments was determined using the hole drilling strain gauge method. The present results indicated that the retained delta ferrite content in type 304 stainless steel weld metals decreased rapid v as nitrogen addition to the argon shielding gas was increased. The welding residual stress increased with increasing quantity, of added nitrogen in the shielding gas. It was also found that the tensile residual stress zone in austenitic stainless steel weldments was exteneded as the quantity of added nitrogen gas in the argon shielding gas was increased. (C) 2002 IoM Commuications Ltd.