Abstract: Based on the principle of multiple factors such as temperature, diffusion, phase transformation and stress, finite element simulation technology was used to simulate and analyze the carburizing process of 20CrMnTi steel under low pressure environment. The simulation process fully considered the boundary condition characteristics of the alternating strong infiltration and diffusion in the low pressure carburizing process, and the strong infiltration and strong infiltration+diffusion were simulated separately, the carbon concentration, martensite volume fraction and hardness distribution were obtained. The results indicate that as the diffusion time increases, the surface carbon concentration of the specimen decreases and the depth of the carburized layer increases. The simulation results of carbon concentration distribution after carburizing are in good agreement with the experimental results, indicating high simulation accuracy. The volume fraction of martensite and hardness of the carburized layer after low pressure carburizing under strong infiltration+diffusion process are simulated, and the distribution of the two is consistent. Comparing the simulation and experimental results of hardness of the specimen after low pressure carburizing under strong infiltration + diffusion process, the measured value is slightly higher than the simulated value, because the simulation result is the calculated average of a larger area.

Key words: low pressure carburizing, 20CrMnTi steel, numerical simulation