硬质合金冲击疲劳行为的研究

Research on Impact Fatigue Behaviour of Cemented Carbide

本文综述了国内外有关硬质合金冲击疲劳行为的研究进展,旨在认识和揭示硬质合金在反复冲击载荷作用下的失效和断裂机理。重点总结了实验室中常用的硬质合金冲击疲劳性能评价方法,包括应力法和能量法;从WC平均晶粒尺寸、粘结相种类及含量、C含量、合金元素(Cr、V、Ta等)、腐蚀介质等方面分析了微观结构和服役环境对硬质合金冲击疲劳性能的影响;从裂纹的萌生、扩展及断裂方面阐述了硬质合金的冲击疲劳断裂机理。服役条件下的硬质合金往往不是受到单一的冲击作用,而是多种因素(载荷、温度、腐蚀介质等)的联合作用,今后有必要开展这方面的研究;另外硬质合金在冲击过程中的组织演变机理还不清楚,研究者可借助更为先进的手段(例如透射电镜原位观察等)对硬质合金的微区进行研究;此外研究者可以在总结试验数据和规律的基础上构建理论及数学模型并借助计算机软件对硬质合金的冲击过程进行动态模拟。

The research progress on the impact fatigue behavior of cemented carbide was reviewed in order to recognize and reveal the failure and fracture mechanisms of cemented carbide under repeated impact load. The methods of evaluation and characterization for the impact properties of cemented carbide mainly used in laboratory, including stress test and energy test. The influences of microstructure and service environment on the impact behaviour of cemented carbide were analyzed from some specific factors, such as load, temperature, service environmen4 WC grain size, kind and content of binder phase, carbon content, alloying element （Cr, V, Ta）, and so on. The fatigue crack initiation, propagation, fracture mechanism and microstructure evolution were also analyzed. In fact, load is not the only factor influencing the service life, but together with other factors, for instance, impulsive load, temperature and corrosion environment. These factors should be and will be the focus in the future research. To better reveal the essence of fatigue, more advanced research techniques, such as TEM in situ observation, can be applied. With the help of computer software, researchers can simulate the dynamic process of cemented carbide and build mathematical models based on summarizing the experimental data.