Study on the Compressive Stress Retention in Quenched Cam of 100Cr6 Steel Based on Coupled Thermomechanical and Metallurgical Modeling

The assembled camshaft has obvious advantages in material optimization and flexible manufacturing. As the most important surface modification technique, the heat treatment process is utilized in this work to promote the desired compressive residual stress on the near-surface of the 100Cr6 steel assembled cam. The Johnson-Mehl-Avrami equation and Koistinen-Marbuger law are integrated into the ABAQUS software via user subroutines to simulate the evolution of diffusional transformation and diffusionless transformation, respectively. The linear mixture law is used for describing the coupled thermomechanical and metallurgical behaviors in the quenching of steel cam. The influences of various quenchants and the probable maximum phase volume fractions on surface residual stress or hardness are analyzed. Results show that a greater amount of martensite volume fraction and a slower martensitic transformation rate are beneficial for the compressive stress retention. Compared with the conventional quenching oil, the fast oil quenched cam surface has higher final compressive stress and hardness.

Automated summary

This study utilized heat treatment process to induce the desired compressive stress near the surface of 100Cr6 steel assembled cam, and simulated diffusional and diffusionless transformations using mathematical models. The research investigated the coupled thermomechanical and metallurgical behaviors during the quenching of steel cam, and analyzed the effects of different quenchants on surface residual stress and hardness. The results indicated that a higher martensite volume fraction and slower martensitic transformation rate are advantageous for stress retention, and fast oil quenching can lead to higher compressive stress and hardness on cam surfaces compared to conventional quenching oil.