Effect of Post-Weld Aging Temperature on Microstructure and Mechanical Properties of Weld Metal of 15-5 PH Stainless Steel

This study is an attempt to correlate the microstructure and mechanical properties of weld metal of commercial 15Cr-5Ni precipitation-hardening stainless steel at different post-weld treatments. The weld metal is conducted by gas tungsten arc welding, and post-weld aging is performed at three different temperatures, viz. 580 °C, 600 °C and 620 °C. After post-weld aging treatment, the microstructure and mechanical properties of weld metals are investigated by OM, SEM, EDS, EBSD and impact tester. The results indicate that microstructure of weld metals by post-weld aging treatment consists predominately of martensite, reversion austenite and copper-rich phase. The amount of austenite and the size of copper-rich phase increase with increase in the post-weld aging temperature. The tensile strength of weld metals first increases and then decreases with the increasing of post-weld aging temperature. The former is due to the size and distribution of copper-rich phase, and the latter is due to the increasing of amount of reversion austenite.