Numerical Simulation and Surface Properties of 42CrMo Steel Treated by Plasma Nitriding and Laser Quenching

Abstract

In this study, we investigated the nitriding and laser quenching composite modified layers of 42CrMo steel. MATLAB was used to fit the nitrogen concentration distribution during nitriding, and the laser temperature field was fitted using ABAQUS finite element simulation software. Two groups of simulation results were integrated to fit the modified layer depth under different processes, and the nitriding and laser quenching experimental results were compared with the simulation results, which indicated that the simulation results agreed well with the experimental results. The depth of the nitriding–laser quenching composite layer greatly improved compared with the nitriding or laser hardening layers. The austenitizing temperature of the 42CrMo steel was reduced to 577 °C by nitriding. Therefore, the depth of the austenitized layer of the 42CrMo steel heated with the same laser power significantly increased. Under the same laser process conditions, more austenitic phase transformation was observed in the nitriding layer than in the non-nitriding layer, so martensitic phase transformation was more likely to occur in the subsequent cooling process. After plasma nitriding at 460 °C for 16 h and laser quenching, the modified layer depth of the 42CrMo steel reached 990 μm, and the average surface hardness of the 42CrMo steel reached 625 HV0.1. The friction coefficient of the modified layer was the lowest, with a value of 0.433, and the minimum wear value was 1.024 mm3. Double hardness and thickness of the modified layer could be obtained by nitriding and laser quenching composite processes.