Affiliation:
1. School of Metallurgy Northeastern University Shenyang 110819 China
2. Liaoning Province Engineering Research Center for Technologies of Low-Carbon Steelmaking Northeastern University Shenyang 110819 China
3. Key Laboratory for Ecological Metallurgy of Multimetallic Ores (Ministry of Education) Northeastern University Shenyang 110819 China
Abstract
In this study, the microstructural evolution of H13 hot‐work die steel during isothermal tempering at 500 ≈ 650 °C is evaluated, and kinetic equations and a neural network are constructed to describe the softening behavior. The results show that the softening behavior appears as a loss of hardness with increasing isothermal tempering temperature and time. The softening mechanism is ascribed to the decomposition of martensitic laths, annihilation and rearrangement of dislocations, formation of sub‐grains, and precipitation and coarsening of secondary carbides. The evolution of secondary carbides includes the coarsening of V‐rich MC nanoprecipitates, and the precipitation and coarsening of secondary phases (Cr‐rich M23C6 and Mo‐rich M6C carbides) during long‐term isothermal tempering. Regarding the applicability of the model in precipitation evolution and hardness prediction, the Johnson–Mehl–Avrami model is considered to be more suitable than the Hollomon–Jaffe, Lifshitz–Slyozov–Wagner, and back‐propagation neural network models.
Funder
National Natural Science Foundation of China
Fundamental Research Funds for the Central Universities
Subject
Materials Chemistry,Metals and Alloys,Physical and Theoretical Chemistry,Condensed Matter Physics