| LUO Liangbin,LIANG Guoxing,LIU Donggang,HAO Xinhui,HUANG Yonggui,ZHAO Jian.Microstructure and Properties of Laser Cladding Co-based Diamond Wear Resistant Layer on 42CrMo Steel Surface[J],53(5):96-107 |
| Microstructure and Properties of Laser Cladding Co-based Diamond Wear Resistant Layer on 42CrMo Steel Surface |
| Received:December 23, 2022 Revised:April 27, 2023 |
| View Full Text View/Add Comment Download reader |
| DOI：10.16490/j.cnki.issn.1001-3660.2024.05.010 |
| KeyWord:laser cladding composite cladding layer microstructure microhardness wear resistance |
| Author | Institution |
| LUO Liangbin |
Shanxi Key Laboratory of Precision Machining, College of Mechanical and Vehicle Engineering,Provincial Technology Innovation Center of Advanced Precision Tool System, Taiyuan University of Technology, Taiyuan , China |
| LIANG Guoxing |
Shanxi Key Laboratory of Precision Machining, College of Mechanical and Vehicle Engineering,Provincial Technology Innovation Center of Advanced Precision Tool System, Taiyuan University of Technology, Taiyuan , China |
| LIU Donggang |
Shanxi Key Laboratory of Precision Machining, College of Mechanical and Vehicle Engineering,Provincial Technology Innovation Center of Advanced Precision Tool System, Taiyuan University of Technology, Taiyuan , China |
| HAO Xinhui |
Shanxi Key Laboratory of Precision Machining, College of Mechanical and Vehicle Engineering,Provincial Technology Innovation Center of Advanced Precision Tool System, Taiyuan University of Technology, Taiyuan , China |
| HUANG Yonggui |
Shanxi Key Laboratory of Precision Machining, College of Mechanical and Vehicle Engineering,Provincial Technology Innovation Center of Advanced Precision Tool System, Taiyuan University of Technology, Taiyuan , China |
| ZHAO Jian |
Shanxi Key Laboratory of Precision Machining, College of Mechanical and Vehicle Engineering,Provincial Technology Innovation Center of Advanced Precision Tool System, Taiyuan University of Technology, Taiyuan , China |
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| Abstract: |
| The work aims to enhance the wear resistance of 42CrMo steel and improve the serious wear failure of 42CrMo steel. The cladding layer with material of diamond/WC particles reinforced Co-based composites was produced on the 42CrMo steel surface by a laser synchronous powder feeding machine. The laser power was 700 W during the cladding process, the powder feeding rate was 21 g/min, the scanning speed of the spot was 180 mm/min, the carrier gas flow rate was 4 L/min, the distance between the substrate and the laser cladding head was 13 mm, and the overlap rate between the adjacent cladding passes was 30%. The polished cross section was corroded with 10% HNO3 alcohol solution to prepare metallographic samples. Macro morphology and microstructure of the cladding layer were observed by SEM and EDS. The phase composition was detected by XRD, the microhardness of the cladding layer was measured by microhardness tester and the friction and wear tests were carried out. The diamond particles pretreated by Ti/TiC powder could improve graphitization and ablation. An appropriate amount of ZrH2 powder could improve the ratio of the width of the cladding layer to its thickness, and promote the convection mass transfer in the molten pool. At the same time, the active element Zr could improve the wettability of diamond and the metal bond could hold the diamond particles strongly. The overlapping cladding layer performed a regular surface and the microstructure of the cladding layer was mainly composed of fine dendrites and dense network carbide eutectic. Rapid melting and freezing velocity at the bonding interface could make all elements diffuse and change in gradient, and generate planar crystals with appropriate dislocation and slip ability. Therefore, the bonding strength between the cladding layer and the substrate was enhanced. The thermal characteristics of laser cladding was contributed to obtain the W2C, ZrC, M6W6C, γ-(Co,Fe), CoZr2, (Ti,Zr)O2, TiCx, Co3Ti and other substances in the laser cladding, and the dispersion distribution of new carbide phase could significantly improve the microhardness of the cladding layer. The average microhardness (1 002HV0.2) of the cladding layer was 3 times that of the substrate due to the fine grain and dispersion strengthening. The average wear mass loss with a value of 1.6 mg was obtained in sliding the cladding layer, which was the 1/2 compared with that in sliding the substrate. The average friction coefficient of the cladding layer was evidently lower than that of the substrate, indicating that the wear resistance of the cladding layer increased. The friction and wear test of the cladding layer showed that abrasive wear became the dominant wear mechanism in sliding the cladding layer, the diamond particles in the cladding layer were passivated, contributing to bearing the friction load. However, the diamond particles located in the wear track on the cladding layer kept an integrity statue and few grains were falling out. The microstructure of the cladding layer is uniform and dense, the microhardness and the wear resistance are significantly improved, so it can be used for surface strengthening of 42CrMo steel. |
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