时效热处理对K417G表面激光沉积CoCrW合金耐磨层组织和性能的影响

    Effect of Aging Heat Treatment on Microstructure and Properties of Laser-deposited CoCrW Wear-resistant Layer on Surfure of K417G Alloy

    • 摘要: 采用激光熔化沉积技术在K417G高温合金表面制备了CoCrW合金耐磨层,研究了时效热处理温度(760、860、960℃)对耐磨层显微组织、物相组成、显微硬度及耐磨性能的影响规律。结果表明:不同时效热处理温度下,耐磨层显微组织均由柱状晶和等轴晶组成,物相主要为γ-Co、M7C3和M23C6;随着时效温度上升,组织中初生共晶碳化物M7C3逐渐分解并与Cr元素产生反应,导致大量细小的碳化物M23C6在M7C3周围二次析出,产生显著细晶强化效果。耐磨层显微硬度与耐磨性能随着时效温度升高呈逐渐增加的趋势,960℃时效处理后耐磨层显微硬度与耐磨性能最优,平均显微硬度为703 HV0.3、摩擦系数为0.26、磨损量仅0.65 mg。

       

      Abstract: A CoCrW alloy wear-resistant layer was prepared on the surface of K417G superalloy by laser melting deposition technology.The effects of aging heat treatment temperatures (760 ℃, 860 ℃, 960 ℃) on the microstructure, phase composition, microhardness and friction and wear properties of the CoCrW alloy wear-resistant layer were investigated. The results show that the microstructure of the wear-resistant layer consists of columnar grains and equiaxial grains at different aging temperatures, and the main phases are γ-Co, M7C3 and M23C6. With the increase of aging heat treatment temperature, the primary eutectic carbide M7C3 in the microstructure is decomposed gradually and reacts with the Cr element, which leads to the secondary precipitation of a large number of fine carbides M23C6 around M7C3 and achieving an obvious grain refinement strengthening effect. The microhardness and wear resistance of the wear-resistant layer increase gradually with the elevation of aging heat treatment temperature, and the hardness and wear resistance of the wear-resistant layer are optimal at 960 ℃. The average microhardness reaches 703 HV0.3, with a friction coefficient of 0.26 and a wear mass loss of only 0.65 mg

       

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