Description:

42CrMo4 materials have been widely used inautomotive driving elements. Although 42CrMo4 is more expensive than 41Cr4, itis more preferable in terms of material properties. In this study, these twomaterials were heat treated by austenitizing in a continuous furnace at850 °C and quenched in oil at 90 °C. After they were tempered atvarious temperatures, mechanical properties were determined for each temperingtemperature. The material properties for both materials were compared with eachother. Results indicated that same mechanical properties for 41Cr4 and 42CrMo4can be achieved by tempering 41Cr4 about 50 °C lower temperature than for42CrMo4. In addition to the mechanical tests, fatigue tests were performed forboth materials. Weibull distributions were plotted. Results indicated that42CrMo4 had a longer life than 41Cr4 material.

Heat Treatment:

·       Forging:Heat to 1150°C Hold until uniform.Minimum forging temperature 850°C. Coolslowly in ashes or sand etc.

·       Annealing:Heat to 830°C – 850°C. Cool in furnace.

·       Normalising:Heat to 870°C – 900°C. Cool in still air.

Stress Relieving:

• Annealed: Heat to 600°C – 650°C
• Hardened: Heat to 500°C – 550°C. Cool in still air
• Hardening:Heat to 830°C – 880°C. Quench in oil or polymer.
• Tempering:Heat to 450°C – 700°C cool in still air.
NB. Tempering within the range 200°C–420°C will result in temper brittlenessand should be avoided Flame and Induction Hardening: Heat quickly to the requiredcase depth at 860°C – 890°C and quench immediately in water or oil. Temperingat 150°C – 200°C will reduce stresses in the case with minimal effect on itshardness. All de-carburised surface material must first be removed to ensurebest results.
• Nitriding: Heat to 500°C – 530°C and hold for sufficient time to develop thedepth of case required Parts should be pre-hardened and tempered as requiredand also premachined leaving a small grinding allowance only.