The Effects of Post-Weld Heat Treatment on the Microstructure and Mechanical Properties of 9% Ni Steel Weld Joint with Fe-Based Filler Material

Abstract

A Fe-based filler material with the composition of Fe-20Ni-5Co-2.5Mn-0.2C was used for welding 9% Ni steel, and the effect of post-weld heat treatment on the microstructure and mechanical properties of the welded joints was investigated. Post-weld heat treatment of the welded joint was performed in the temperature range of 200 to 600 ℃. After the experimental selection, the microstructure changes of the weld metal and base metal were investigated in detail at heat treatment temperatures of 350 and 600 ℃. Grain morphology, size, and the location of precipitated cementite were studied using SEM and EBSD phase maps. The mechanical properties of the weld joint were characterized by tensile properties and micro-hardness. Based on the experimental results, this study provides key insights into the applicability of post-weld heat treatment to weld joints of 9% Ni steel prepared using Fe-based filler material to improve the mechanical properties, toughness and ductility of the weld joints.