AISI 4340 steel is widely used in high risk industries due to its excellent mechanical strength and impact resistance. The mechanical properties of AISI 4340 steel can be significantly enhanced through heat treatment, particularly tempering at controlled temperatures. This study investigates the effect of tempering on the microstructure and mechanical properties of AISI 4340 steel. The experimental analysis includes characterization before and after heat treatment to assess changes in strength, toughness, and ductility. The results demonstrate that tempering at 450?C for 45 minutes optimally improves impact energy and ductility while slightly reducing hardness and strength. Conversely, tempering at 550?C results in a more pronounced increase in impact energy and ductility, but at the cost of a greater reduction in hardness and strength. Microstructural examination confirms the formation of tempered martensite, contributing to the observed mechanical behavior. The findings provide valuable insights into optimizing heat treatment parameters for AISI 4340 steel to achieve a balanced combination of strength, toughness, and ductility for industrial applications.
Ali et al. (Thu,) studied this question.