科研之友
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摘要
Medium manganese martensitic wear-resistant steel is a new type of wear-resistant steel with high hardenability and hardness; moreover, the controlling austenite grain size is of great significance for improving its comprehensive properties. In this study, the austenite growth behavior of vanadium microalloying medium manganese martensitic wear-resistant steel was systematically investigated using the Gleeble-3500 thermal simulation testing machine, OM, and HRTEM. The morphology, size, and particle size distribution of the second phase particles at different heating temperatures and holding times were analyzed. The influence of second phase particles on the growth behavior in austenite was also revealed. The results showed that the ultra-fine austenite grains with grain size of 3.98 mu m were obtained when the sample was held at 820 degrees C for 10 s. After holding for 3600 s, the average grain size of austenite only increased by 1.47 mu m, and the austenite grains showed a strong ability to resist coarsening at 820oC. This could be attributed to the fine V(C, N) particles which could pin the austenite grain boundary and inhibit the growth of austenite grains. Furthermore, when reheating temperatures and holding times increase, the dissolution and coarsening of V(C, N) particles lead to the decrease of pining ability and then to the rapid growth of austenite. A new Sellars model with a time index was used to establish austenite growth model using a new method with a predetermined error function. The accuracy of the prediction for austenite grain sizes with new Sellars model was greatly improved compared with the traditional Beck model.
