Evaluation of Cross-Weld Properties of Austenitic Stainless Steels Before and After PWHT

Different types of austenitic stainless steels, which are commonly used for piping systems, tanks, and vessels, required postweld heat treatment (PWHT), at temperatures between 540 and 590 °C, regardless of the plate thickness. This paper reports on the weld procedures and cross-weld performance evalution of weldments in 6 mm AISI 304L, 316L, and 347 steel plates before and after PWHT. This welds were produced by SMAW and GTAW techniques using a single vee preparation and multiple weld beads, and welded by various types of consumables. After PWHT, tensile tests indicated a reduction in the ultimate tensile strength of all samples and a decrease in the yield strength for some cases only. The hardness results were consistent with the tensile test results because they both revealed significant softening in the HAZ and WM as a result of PWHT. In spite of the fact that PWHT exerts a beneficial effect on reducing residual stresses, it is concluded that the ductility of the weld region was satisfactory without PWHT, and PWHT decreased the cross-weld tensile strength.