Effect of primary annealing and normalizing treatment before quench-temper treatment on tool wear of 42CrMo4 steel

The purpose of this study was to investigate the effect of primary annealing and normalizing on the tools wear properties of the 42CrMo4 steel after hardening and temper treatment. For this purpose, after annealing and normalizing heat treatment, the samples were austenitized at a temperature of 860 ° C for 100 minutes and then were placed in quenched oil and then subjected to temper heat treatment at a temperature of 400 ° C for 60 minutes. Laboratory tests included tests of hardness, microscopic structure and life measurements of cutting tools on samples. The results showed that although the structure of both specimens contains martensite, since coarser structure has been obtained in the annealed specimen, coarser martensite packs compared to the normalized sample have been produced. This reduces the hardness of annealed quench-temper samples compared to the normalized quench-temper samples therefore, the machining properties of the annealed quench-temper specimens are more appropriate. The results of this study showed that the cutting tool life at cutting speed of 65 (m/min) in the annealed and normalized quench-temper samples was 75 and 65 minutes, respectively and, at cutting speed of 90 (m/min) it is 50 and 45 minutes, respectively.