| ZHANG Daoda,ZHAO Longzhi,LIAN Yong,ZHOU Hongbo,WU Xiaoquan,MENG Yang.Effect of Laser-induced Nanization of Stainless Steel Surface on Microstructure and Properties of Nitrocar-burizing Layer[J],53(21):153-161 |
| Effect of Laser-induced Nanization of Stainless Steel Surface on Microstructure and Properties of Nitrocar-burizing Layer |
| Received:November 07, 2023 Revised:December 26, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.21.016 |
| KeyWord:laser shock austenitic stainless steel nitrocar-burizing electrochemistry microhardness |
| Author | Institution |
| ZHANG Daoda |
College of Materials Science and Engineering, East China Jiaotong University, Nanchang , China;Jiangxi Institute of Mechanical Science, Nanchang , China |
| ZHAO Longzhi |
College of Materials Science and Engineering, East China Jiaotong University, Nanchang , China |
| LIAN Yong |
Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing , China |
| ZHOU Hongbo |
Jiangxi Institute of Mechanical Science, Nanchang , China |
| WU Xiaoquan |
Jiangxi Institute of Mechanical Science, Nanchang , China |
| MENG Yang |
Jinan Shengyang High Temperature Material Co., Ltd., Jinan , China |
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| Abstract: |
| Stainless steel nitrocar-burizing is to dope nitride and carbon elements on the surface of stainless steel, so as to improve the wear resistance and corrosion resistance of the material. Laser shock hardening is a new surface strengthening technology which uses laser shock wave to produce plastic deformation on metal surface, increase the surface dislocation density, and improve the hardness and fatigue resistance of the metal surface. The change of metal surface microstructure caused by laser shock treatment is beneficial to the adsorption and diffusion of N atom in subsequent ion nitriding, so as to significantly improve the efficiency of ion nitriding. However, there are few researches about the effect of laser shock energy on the microstructure and properties of ionitrocarburizing layer. In this study, the 316 stainless steel surface was treated by laser shock with four different energy densities, followed by low temperature ionitrocarburizing, and the effects of different laser shock energies on the structure and properties of ionitrocarburizing stainless steel were analyzed by various characterization methods. Three kinds of impact energy of 0, 20 and 30 J were used to laser shock the stainless steel, and then the stainless steel was treated at 480 ℃ for ion nitrogen carburizing and subject to heat preservation for 5 h. The gas source was ammonia and argon + C4H4 (9∶1) mixed gas and the ratio was 1∶1. The microstructure, composition and phase structure of the infiltration layer were analyzed by SEM, ED-MS and XRD. The hardness, friction coefficient and corrosion resistance of the permeated layer were tested by microhardness tester, friction and wear machine and electrochemical workstation. The three kinds of stainless steel specimens could be divided into three layers, including the outer fine crystal zone, the middle coarse crystal transition zone and the inner deformation affected zone. In terms of phase structure, the infiltration layer was divided into two layers, in which the outer layer was N-rich layer dominated by SN, and the inner layer was C-rich layer dominated by Sc phase at the junction of the matrix. The phase of the permeated layer of the three stainless steel specimens was composed of S phase, gamma phase, alpha phase and Cr2N. After laser shock, the S-phase content of the nitrocarburizing layer significantly increased, the gamma phase significantly decreased, and the alpha phase content also significantly increased. Compared with the specimen with 20 J energy, the penetration thickness, microhardness and friction and wear properties of the specimen treated with 30 J laser shock were only slightly improved, and the corrosion resistance even deteriorated. The permeated layers of the specimens pretreated with 20 J and 30 J have both good corrosion resistance and wear resistance. |
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