Abstract
The subject of investigation was the effect of post-weld heat treatment (PWHT) on mechanical properties, hardness distribution across the welded joints, and on the microstructure of AISI 316L austenitic stainless steel weld metal. Steel plates of 15 mm thickness were welded by manual electric arc welding and treated at 600-900 °C. The tensile strength increased and impact energy values decreased with the increasing annealing temperature. The hardness test results for the weld metal, which were approximately equal before PWHT and after it, were higher than those for the base metal and the heat-affected zone. The weld metal microstructure was examined by means of an optical microscope and a scanning electron microscope. It demonstrated the presence of austenite, ferrite and microslag inclusions before PWHT, and that of sigma phase after PWHT. Also, the presence of complex Mn-Cr-Si-Ti inclusions in small holes was observed in tensile and impact (Charpy) tested specimens.

Key words
austenitic stainless steel, welding, mechanical properties, microstructure, sigma phase

Full text (622 KB)