Microstructure and wear behavior of arc-shaped 40CrNiMo steel after laser hardening

This study focuses on arc-shaped 40CrNiMo steel; the microstructure characteristics and formation mechanism of the hardened layer at different positions were investigated after laser hardening. Moreover, sliding friction experiments were conducted against GCr15 steel after the conventional heat treatment under dry friction conditions, and the wear characteristics of 40CrNiMo steel hardened after different laser process parameters was analyzed, the wear mechanism in different wear stages was studied. The results show that the martensite reliefs within different austenite grains have no effect on each other. The martensite relief within each individual austenite grain is closely related to the martensite growth in that grain. The laser hardening process parameters for obtaining the effective wear resistance performance of arc-shaped 40CrNiMo steel are as follows: the power was 2010 W, the spot size was 1 × 14 mm2 and the scanning speed was 800 mm/min. At the beginning of the friction wear tests, the wear type of arc-shaped 40CrNiMo steel is mainly abrasive wear. Abrasive wear causes spalling, and oxidation wear can easily occur at the peeling sites. As the dry friction wear tests continued, both oxidation wear and adhesive wear increased, and fatigue wear gradually occurred. The wear mechanism of the grinding plate with a similar hardness at different stages is similar to that of the circular-arc specimen.