目的 通过诱发纳米孪晶强化贝氏体化涂层强度及耐磨性。方法 在 250 ℃对中碳合金钢进行激光熔覆，并进行等温处理。通过残余应力测试、X 射线衍射试验、扫描电子显微镜和透射电子显微镜观察、显微硬度和纳米压痕测试、往复磨损试验及磨损形貌表征，分别评价激光熔覆涂层的残余应力、物相、显微组织与结构、硬度梯度及微观硬度\耐磨性能。结果 激光熔覆涂层平行和垂直激光移动方向的平均应力值分别为(209±20) MPa和(319±21) MPa。激光熔覆引入大量位错结构，使残余奥氏体尺寸降低至(37.5±2.5) nm。两组试样均为无碳化物贝氏体组织，其显微组织由针状的贝氏体铁素体以及残余奥氏体组成。在激光热作用及后续等温过程中，显微组织明显细化，并伴随生成大量塑性良好的纳米孪晶结构。激光熔覆涂层的平均显微硬度为 650HV，较基体的平均硬度提升了约 25%。相同磨损时间下，熔覆层的磨损体积为 0.675 mm3， 基体的磨损体积为 1.142 mm3，纳米孪晶结构的形成大大提升了中碳合金钢的抗粘着磨损性能。结论 在特定温度对中碳合金钢进行激光熔覆可以制备贝氏体化涂层，在热应力作用下，显微组织中形成的纳米孪晶结构能够对涂层增强增韧，同时提高其抗粘着磨损性能。

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.