The effect of annealing on properties of AISI 316L base and weld metals

Results of mechanical testing and of microstructural analysis of AISI 316L austenitic stainless steel carried out before and after welding and post-weld heat treatment are presented. Steel plates of 15 mm thickness were welded by manual electric arc welding process. Heat treatment consisted of annealing at 600, 700, 800, and 900 °C for two hours, and was followed by cooling in the air. For microstructure examination an optical microscope and a scanning electron microscope were used. The weld metal microstructure demonstrated the presence of austenite, ferrite, and microslag inclusions before annealing, and of sigma phase after annealing. The tensile strength increased and impact energy values decreased with the increasing annealing temperature. Complex Mn-Cr-Si-Ti inclusions in the dimples were observed in the tensile and Charpy tested specimens.