The Effect of Heat Treatment on Mechanical Properties and Microstructure of the AISI 422 Martensitic Stainless Steel
Martensitic stainless steel has a wide range of applications in steam generators and food industries like mixing blades due to high mechanical and good corrosion resistance. In this research, the effect of austenitizing temperatures (1040°C -1070°C), tempering temperatures (300, 400, 500, 600 and 700°C) and also the tempering times of (2 and 5 h) on microstructure and mechanical properties of martensitic stainless steel X20CrMoWV121(AISI 422) has been investigated. The results of the experiments showed that with increasing the austenitizing temperature from 1040 to 1070°C the impact energy is reduced, and the hardness and yield strength are increased. These changes are due to the increase in the austenite grain size. The secondary hardness occurs in the tempering temperature in range of 400-500°C.The results revealed that after tempering, an increase in hardness and strength and a reduction in toughness occurred in the samples. Also, with increase in the tempering time from 2 to 5 hours at 700°C, the toughness increased and hardness as well as strength were reduced due to the precipitation of the carbides.