The effect of a single quenching double tempering process on the mechanical properties of NiCrMo alloyed steel casting

Abstract

This research aimed to improve the mechanical properties of NiCrMo alloyed steel casting, especially in terms of toughness. Toughness is a combination of tensile strength, yield strength, and elongation. The method used was a multi-heat treatment process involves normalizing, tempering, double tempering, and an additional intermediate process of quenching. The results obtained through the normalizing process followed by single quenching on oil media and double tempering (single quenching double tempering) produced the best-combined result of tensile strength, yield strength, and elongation. The modulus of toughness increased by up to 745 % compared to the as-cast condition from 20 N.mm/mm3 to 149 N.mm/mm3. The best mechanical properties were obtained from tempered martensite microstructure. It is free from rest martensite and secondary carbide.