Influence of Sintering and Heat Treatment on the Microstructure, Mechanical Properties, and Tribological Performance of AlTiN-Coated PM M42 High-Speed Steel.
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| Title: | Influence of Sintering and Heat Treatment on the Microstructure, Mechanical Properties, and Tribological Performance of AlTiN-Coated PM M42 High-Speed Steel. |
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| Authors: | Qi, Zijun1 (AUTHOR) 2303082500009@stu.nchu.edu.cn, Chen, Yi1,2 (AUTHOR), Li, Ji2,3 (AUTHOR), Huang, Yongde4 (AUTHOR), Wang, Qian1,3 (AUTHOR), Wei, Qi2,3 (AUTHOR) huangydhm@tzc.edu.cn, Yang, Xiaofeng3 (AUTHOR), Liu, Qiang1,4 (AUTHOR) |
| Source: | Materials (1996-1944). Apr2026, Vol. 19 Issue 8, p1667. 24p. |
| Subjects: | Sintering, Heat treatment, Surface coatings, Tool-steel, Wear resistance, Mechanical behavior of materials, Microstructure |
| Abstract: | Highlights: Elevating the sintering temperature promoted densification of M42 high-speed steel, thereby concurrently improving both its hardness and bending strength (σ). Microstructural evolution during austenitizing, consistent with a possible phase transformation from M2C to MC and M6C, leads to a trade-off between strength and toughness. The hardness exhibits an initial increase followed by a subsequent decrease, reaching a peak value of 868 HV at 60 min, while the bending strength decreases monotonically. The microstructural evolution of the matrix carbides appears to enhance the wear resistance of the AlTiN coating by synergistically regulating the microstructure and mechanical properties (Vickers hardness, bending strength σ, and interfacial bonding strength LC) of the matrix. The AlTiN coating deposited on the M42 high-speed steel substrate sintered at 1190 °C and austenitized for 120 min exhibits the lowest wear rate (2.38 × 10−6 mm3·N−1·m−1), demonstrating superior wear resistance. Preparing a highly wear-resistant AlTiN coating on a powder metallurgy (PM) M42 high-speed steel substrate is a key strategy to enhance tool performance and meet the demands of efficient machining. This study adopted a process route comprising substrate preparation, heat treatment regulation, and arc-PVD deposition of AlTiN coatings to systematically investigate the influence of sintering temperature (1130, 1160, and 1190 °C) and austenitizing time (1150 °C for 0, 15, 60, and 120 min) on the microstructure and mechanical properties of the substrate, as well as on the tribological performance of the AlTiN coatings. The results indicate that elevating the sintering temperature promotes densification of the matrix, with Vickers hardness increasing from 366 HV to 462 HV and bending strength (σ) increasing from 1064 MPa to 1310 MPa. The predominant carbide phases identified are MC, M2C, and M6C. During austenitizing, microstructural changes consistent with a progressive transformation from M2C to MC and M6C carbides were indicated by SEM and XRD analyses. Precipitation strengthening was most evident after 60 min, with hardness reaching 868 HV. In contrast, bending strength (σ) exhibited a progressive decline with increasing austenitizing time, decreasing from 1310 MPa to 1015 MPa after 120 min, illustrating a clear trade-off between hardness and toughness. The wear behavior of the coating is governed synergistically by substrate hardness, bending strength (σ), coating–substrate interfacial adhesion strength (LC), and carbide phase transformation. Elevated substrate hardness enhances anti-wear performance; bending strength influences crack propagation and spallation tendency; and LC determines the efficiency of interfacial load transfer. The carbide phase evolution appears to modulate the coating's wear behavior by regulating both the microstructure and mechanical properties of the substrate. Among the six sample conditions evaluated, the A3 sample (sintered at 1190 °C and austenitized for 120 min) exhibited the lowest wear rate (2.38 × 10−6 mm3·N−1·m−1), demonstrating superior wear resistance. These findings provide a reference for process optimization and rational design of M42/AlTiN composite coating systems. [ABSTRACT FROM AUTHOR] |
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| Abstract: | Highlights: Elevating the sintering temperature promoted densification of M42 high-speed steel, thereby concurrently improving both its hardness and bending strength (σ). Microstructural evolution during austenitizing, consistent with a possible phase transformation from M2C to MC and M6C, leads to a trade-off between strength and toughness. The hardness exhibits an initial increase followed by a subsequent decrease, reaching a peak value of 868 HV at 60 min, while the bending strength decreases monotonically. The microstructural evolution of the matrix carbides appears to enhance the wear resistance of the AlTiN coating by synergistically regulating the microstructure and mechanical properties (Vickers hardness, bending strength σ, and interfacial bonding strength LC) of the matrix. The AlTiN coating deposited on the M42 high-speed steel substrate sintered at 1190 °C and austenitized for 120 min exhibits the lowest wear rate (2.38 × 10−6 mm3·N−1·m−1), demonstrating superior wear resistance. Preparing a highly wear-resistant AlTiN coating on a powder metallurgy (PM) M42 high-speed steel substrate is a key strategy to enhance tool performance and meet the demands of efficient machining. This study adopted a process route comprising substrate preparation, heat treatment regulation, and arc-PVD deposition of AlTiN coatings to systematically investigate the influence of sintering temperature (1130, 1160, and 1190 °C) and austenitizing time (1150 °C for 0, 15, 60, and 120 min) on the microstructure and mechanical properties of the substrate, as well as on the tribological performance of the AlTiN coatings. The results indicate that elevating the sintering temperature promotes densification of the matrix, with Vickers hardness increasing from 366 HV to 462 HV and bending strength (σ) increasing from 1064 MPa to 1310 MPa. The predominant carbide phases identified are MC, M2C, and M6C. During austenitizing, microstructural changes consistent with a progressive transformation from M2C to MC and M6C carbides were indicated by SEM and XRD analyses. Precipitation strengthening was most evident after 60 min, with hardness reaching 868 HV. In contrast, bending strength (σ) exhibited a progressive decline with increasing austenitizing time, decreasing from 1310 MPa to 1015 MPa after 120 min, illustrating a clear trade-off between hardness and toughness. The wear behavior of the coating is governed synergistically by substrate hardness, bending strength (σ), coating–substrate interfacial adhesion strength (LC), and carbide phase transformation. Elevated substrate hardness enhances anti-wear performance; bending strength influences crack propagation and spallation tendency; and LC determines the efficiency of interfacial load transfer. The carbide phase evolution appears to modulate the coating's wear behavior by regulating both the microstructure and mechanical properties of the substrate. Among the six sample conditions evaluated, the A3 sample (sintered at 1190 °C and austenitized for 120 min) exhibited the lowest wear rate (2.38 × 10−6 mm3·N−1·m−1), demonstrating superior wear resistance. These findings provide a reference for process optimization and rational design of M42/AlTiN composite coating systems. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 19961944 |
| DOI: | 10.3390/ma19081667 |
