Alloy steel possesses high strength, hardenability, fatigue strength, and good
impact toughness. It is widely used for making various machine parts, automobile
components, shafts, gears, connecting rods, and more. Hardening and tempering
develop the optimum combination of hardness, strength, and toughness in
engineering steel, thereby providing components with high mechanical properties.
Hardening and tempering temperatures are crucial factors that affect the
mechanical and metallurgical properties of 42Cr4Mo steel. In this research work,
42Cr4Mo alloy steel samples were subjected to hardening and tempering processes.
The hardening temperatures were set at 830°C, 850°C, and 870°C, while the
tempering temperatures were maintained at 590°C and 650°C. The test results show
that hardening at 830°C and tempering at 590°C achieve high tensile strength,
which decreases as the temperature increases. Different hardening temperatures
and constant tempering temperatures will be optimized to achieve the desired
hardness, ultimate tensile strength, yield strength, impact resistance, and
metallurgical properties. These parameters significantly contribute to
determining the appropriate.