Microstructure analysis and yield strength simulation in high Co–Ni secondary hardening steel

The microstructure of AerMet100 steel after aging was observed and analyzed. Based on the microstructure information of AerMet100 with different aging temperature, equivalent radius of M2C carbides was calculated and used in modified Wang's model to simulate the relation between yield strength and aging temperature. The simulation results showed that AerMet100 was mainly strengthened by M2C precipitate and solid solution. Solid solution strengthening decreased with the increasing of aging temperature because the growth of M2C and austenite gradually consumed Cr, Mo, Ni and C in the matrix. M2C strengthening was controlled by the opposite effect of growth rate and nucleation rate of M2C on strength. By adding the effect of austenite into the model and making simplification, the simulation results of the modified Wang's model were closer to the experiment results than the original Wang's model.