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Microstructural Evolution and Carbide Precipitation in a Heat-Treated H13 Hot Work Mold Steel
Mu Lin, Xingfeng Zhao, Lizhan Han, Qingdong Liu, Jianfeng Gu
Keywords:H13steel；Microstructure Heat treatment；Carbide Characterization；
Abstract: The microstructure and carbide precipitation for a H13 hot work mold steel after heat treatment and stabilization treatment at 620 °C for up to 20 h were investigated by optical microscopy, electron backscatter diffraction, and transmission electron microscopy. After solutionization at 1020 °C for 40 min followed by oiling cooling and double tempering at 610 °C for 2 h, lathlike martensitic structure was obtained with various alloyed carbides including Cr-rich M23C6 carbide located at prior austenite grain boundaries or lath boundaries and V-rich MC and Mo-rich M2C carbides distributed in grain interiors. The heat-treated sample had high strength surpassing 1000 MPa at room temperature and 500 MPa at 650 °C. After stabilization treatment at 620 °C for 20 h, the carbides underwent limited coarsening, particularly for the MC and M2C carbides, which resulted in excellent resistance to tempering softening for the microstructure as the hardness surpassed 300 HV.
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