Effect of tempering temperature on impact energy of AISI 410 martensitic stainless steel at low temperatures

Abstract AISI 410 martensitic stainless-steel specimens were austenitized at 1253 K then oil quenched and tempered at 573, 673, 773 and 923 K for 3600 s. The impact energy of the specimens was tested at 298, 253, 223, 213 K and measured using ASTM E23 standard. After austenitizing and tempering, the microstructure of the specimens showed carbide precipitation. Tempering at 773 K resulted in the highest hardness due to secondary hardening, while tempering at 923 K resulted in the lowest hardness due to brittle carbide precipitation at the grain boundary which caused softening of the matrix by decreasing the solute carbon content. By contrast, the change in impact energy is inversely proportional to the hardness values. The impact surface of specimens tempered at 573, 673 and 773 K revealed transgranular fracture; on the other hand, the impact surface of the specimen tempered at 923 K revealed intergranular fracture. From our experimental results, the appropriate hardening and tempering procedure of AISI 410 for low temperatures applications is selectable.