| ZHOU Ye-fei,WANG Shao-feng,XING Xiao-lei,YANG Qing-xiang.Bainite Coating Strengthened by Nano-twins and Its Wear Resistance[J],47(8):1-7 |
| Bainite Coating Strengthened by Nano-twins and Its Wear Resistance |
| Received:March 23, 2018 Revised:August 20, 2018 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2018.08.001 |
| KeyWord:laser cladding bainite coating residual stress nano-twins wear resistance |
| Author | Institution |
| ZHOU Ye-fei |
1.School of Mechanical Engineering, Yanshan University, Qinhuangdao , China; 2.State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao , China |
| WANG Shao-feng |
1.School of Mechanical Engineering, Yanshan University, Qinhuangdao , China; 2.State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao , China |
| XING Xiao-lei |
1.School of Mechanical Engineering, Yanshan University, Qinhuangdao , China; 2.State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao , China |
| YANG Qing-xiang |
State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao , China |
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| Abstract: |
| To improve strength and wear resistance of bainite coating by inducing nano-twins. Medium carbon alloy steel was laser cladded at 250 ℃ with the following isothermal treatment at the same temperature. Residual stress, phases, microstructures, gradient hardness, micro-hardness and wear resistance of the laser cladding were analyzed by residual stress powder diffraction, XRD, SEM, TEM, microhardness tester, nanoindentation and reciprocating friction and wear tester. The average residual stress of the coating in the direction of parallel and vertical laser movement was (209±20) MPa and (319±21) MPa, respectively. A large number of dislocation structures were induced during laser cladding which in turn reduced the size of retained austenite to (37.5±2.5) nm. The microstructure of the samples was typically non-carbide bainite, which consisted of acicular bainitic ferrite and retained austenite. The microstructure could be refined by laser thermal process with the following isothermal treatment accompanied by the formation of a large number of plastic nano-twins. The average microhardness of the coating was 650 HV, an increase of about 25% compared to the average hardness of the substrate. The wear volume of the coating and substrate is 0.675 mm3 and 1.142 mm3, respectively, which inferred that the anti-adhesive wear resistance of the coating was improved by the formation of nano-twins. The bainite coating can be prepared by laser cladding of medium carbon alloy steel at a specific temperature. Under the action of thermal stress, nano twins formed in the microstructure can strengthen and toughen the coating and improve its adhesive wear resistance. |
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