| HE Xiao-rong,LI Qiu-ping,LIU Shao-peng,SHEN Ming-xue.Tribological Properties of Nitriding Layer of Cr12MoV Die Steel in Different Wear Stages during Service[J],51(8):243-251, 271 |
| Tribological Properties of Nitriding Layer of Cr12MoV Die Steel in Different Wear Stages during Service |
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| DOI：10.16490/j.cnki.issn.1001-3660.2022.08.020 |
| KeyWord:Cr12MoV die steel gas nitriding microhardness wear resistance wear mechanism |
| Author | Institution |
| HE Xiao-rong |
School of Material Science and Engineering , Nanchang , China |
| LI Qiu-ping |
School of Material Science and Engineering , Nanchang , China;Key Laboratory of Conveyance and Equipment, Ministry of Education, East China Jiaotong University, Nanchang , China |
| LIU Shao-peng |
School of Material Science and Engineering , Nanchang , China |
| SHEN Ming-xue |
School of Material Science and Engineering , Nanchang , China;Key Laboratory of Conveyance and Equipment, Ministry of Education, East China Jiaotong University, Nanchang , China |
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| Abstract: |
| Cr12MoV can be considered as one of the most widely used cold working die steel due to its excellent comprehensive performance, such as good hardness and toughness, and high compressive strength. However, the cold working die steel often withstand extremely high circulating pressure, cutting force and high impact force during industrial applications, resulting in the production of crack sources such as scratching and peeling on the surface, which ultimately leads to the failure of cold working die. Generally, nitriding treatment is one of the most economic methods to enhance the comprehensive performance of cold working die steel, but the present researches mainly focus on the effects of nitriding process parameters on the microstructure evolution, hardness and wear resistance of die steel, few studies are dedicated to the tribological properties and corresponding wear mechanism of die steel at different wear stages after nitriding treatment. In order to understand the effect of nitriding treatment on the wear resistance of Cr12MoV die steel and provide a theoretical basis for the wear behavior of nitriding layer in different wear stages during service, the microstructure of Cr12MoV die steel after nitriding treatment and the tribological characteristics of nitriding layer at different sampling thickness are analyzed. The Cr12MoV die steel is treated by gas nitriding at constant temperature, the effect of nitriding treatment on the microstructure of Cr12MoV die steel and the wear behavior and corresponding wear mechanism of nitriding layer at different sampling thickness are studied in detail. The results show that a compact layer with a thickness of about 120 μm is formed on the surface of Cr12MoV die steel, resulting in the increased microhardness from 3.65 GPa to 12 GPa, while the depth of wear marks reduces from 3.5 μm to 0.35 μm. With the increase of the distance between the sampling position and the coating surface, the abrasion loss of the sample increases gradually, but it is still far lower than that of the substrate. Among them, the maximum wear of the nitriding layer is about 120 μm3, which is approximately 1/10 of the base material. The maximum wear of nitriding affected area is about 330 μm3, which is almost 1/3 of the matrix. Therefore, gas nitriding treatment can significantly enhance the wear resistance of Cr12MoV die steel. Moreover, the Cr12MoV die steel is seriously worn during the wear process, resulting in large tear damage, and the dominant wear mechanism is fatigue wear. After nitriding treatment, the surface damage of the nitriding layer is slight, and the dominant wear mechanism is abrasive wear. However, with the increasing distance between the sampling position and the coating, the wear phenomenon of the samples gradually intensifies, and the dominant wear mechanism changes from abrasive wear to fatigue wear. Thus, nitriding treatment can form a dense nitriding layer on the surface of Cr12MoV die steel, and the wear amount of nitriding layer will first decrease and then continue to increase with the increase of sampling thickness, indicating that the wear resistance of nitriding layer increases first and then decreases during service. Therefore, the nitriding treatment can significantly improve the wear resistance of cold-working die steel and the service life of the cold work die, which has vital practical significance in industrial applications. |
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