EVALUATION OF RESIDUAL STRESSES IN BIMETALLIC WELDS

Abstract

Dissimilar metal joints between plates of mild steel and austenitic steel are widely used in various fields like nuclear power plant. Failure analysis carried out on dissimilar joints and literature review have shown that a significant number of failure have occurred in the heat affected zone of the dissimilar welded joints residual stresses present in the welded joints are one of the main factors which cause failure in dissimilar welded joints. In the present study plain carbon steel SA 516 and austenitic stainless steel AISI 304 L were joined by the GTAW processes using an austenitic stainless steel AISI 308L filler metal. A buttering layer of ER309L with different thickness were laid on plain carbon steel to prevent carbon migration from mild steel to weld metal .Residual stresses were determined in the dissimilar welded joints using stain gauge hole drilling method. Investigation was carried out to assess the effect of variation in the buttering layer thickness on residual stresses in different zones in weld coupons. Tensile test, Impact test, microhardness test were also performed to check the ultimate tensile strength ,yield strength, impact strength, microhardness of weld metal .