对YG8和YG25两种WC-Co硬质合金不同时间深冷处理后的力学性能和疲劳性能进行了研究,利用X射线衍射方法分析了深冷前后合金的相变和残余应力变化,通过扫描电子显微镜（SEM）观察了材料的断口形貌和断裂方式。结果表明：深冷处理能有效提高了WC-Co硬质合金的硬度、强度、耐磨性和疲劳寿命。深冷处理时间是最主要的工艺参数,对YG8合金来说,2 h为深冷处理最佳工艺时间,而YG25则为8 h。其性能变化的主要原因是深冷处理导致硬质合金表面残余应力的变化和Co粘结相发生马氏体相变。
Effect of cryogenic treatment on mechanical and fatigue properties of YG8 and YG25 cemented carbides was investigated.The results show that hardness and compression strength of the samples treated by cryogenic environment are higher than those of the untreated ones,while the bending strength remains unchanged.The cryogenic treated alloys produce superior wear resistance to the alloys without cryogenic treatment.The material exhibits higher fatigue resistance after cryogenic treatment than the untreated ones.The change of properties is highly dependent on the soaking time of cryogenic treatment and YG8 shows the best result at 2 h,while YG25 is 8 h.The main reason for the change of mechanical,wear resistance and fatigue properties can be ascribed to the change of residual stresses and martensitic phase transformation from α-Co（FCC） to ε-Co（HCP） in the cryogenic-treated WC-Co cemented carbides.
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