Chen Jinpeng,Wang Haojie,Chen Cheng,et al.Microstructure Evolution and Mechanical Property Control of H13 Hot-work Die Steel during Tempering[J].Special Steel,2026,47(05):87-95.
Chen Jinpeng,Wang Haojie,Chen Cheng,et al.Microstructure Evolution and Mechanical Property Control of H13 Hot-work Die Steel during Tempering[J].Special Steel,2026,47(05):87-95.DOI:10.20057/j.1003-8620.N260083.
Microstructure Evolution and Mechanical Property Control of H13 Hot-work Die Steel during Tempering
Taking as-cast H13 hot-work die steel as the research material, specimens were austenitized at 1 100 ℃ for 20 min followed by oil quenching, and subsequently subjected to tempering treatments at 560 ℃, 620 ℃ and 650 ℃ with varying tempering durations and cycles. Optical microscopy (OM), scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), electron backscatter diffraction (EBSD), hardness measurements and Charpy impact tests were employed to investigate the effects of tempering parameters on microstructure evolution and mechanical properties of the steel. The results reveal that tempering temperature dominates the microstructure evolution of H13 steel. With increasing tempering temperature, time and number of cycles, the lath feature of martensite gradually weakens; precipitated fine dispersed carbides undergo aggregation, spheroidization and coarsening, while the retained austenite content and dissolved carbon content in martensite show an overall decrease, and the microstructure evolves from tempered martensite to high-temperature tempered microstructure. Tempering at 560 ℃ retains relatively high hardness, among which the group tempered at 560 ℃ for 65 min with three cycles achieves the maximum hardness of 54.6 HRC, yet a low impact absorbed energy. Tempering at 650 ℃ accelerates matrix recovery and carbide spheroidization, and the group tempered at 650 ℃ for 65 min with two cycles achieves the highest impact absorbed energy of 15.39 J with superior impact toughness. The fracture morphology gradually transforms from cleavage/quasi-cleavage fracture at low tempering temperature to dimple ductile fracture at high tempering temperature. Optimized regulation of tempering temperature, time and number of cycles enables synergistic improvement in hardness and toughness of H13 steel.
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