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通过两种疲劳试验:旋转弯曲疲劳试验和3-或4-点弯曲疲劳试验测试细晶WC-Co硬质合金的裂纹生长行为和疲劳寿命。疲劳试验结果表明:所测试的大部分WC-Co硬质合金的疲劳寿命取决于裂纹生长周期。利用断裂力学基本方程推导出疲劳裂纹生长速率(da/dN)和最大应力强度因子(Kmax)的关系。根据此关系,获得材料的强度因子阈值(Kth)和疲劳断裂韧性值(Kfc)。基于修正的线性弹性断裂力学方程,对WC-Co硬质合金材料的疲劳寿命进行计算,疲劳寿命的计算结果与实验结果吻合较好。
Tensile fatigue behavior and fatigue life of the fine grained WC-Co cemented carbide were tested by two types of fatigue tests: rotation bending fatigue test and 3- or 4-point bending fatigue test. Fatigue test results show that the fatigue life of most WC-Co cemented carbides tested depends on the crack growth cycle. The relationship between fatigue crack growth rate (da / dN) and maximum stress intensity factor (Kmax) was deduced by using the basic equations of fracture mechanics. Based on this relationship, the material’s strength factor threshold (Kth) and the fatigue fracture toughness value (Kfc) were obtained. Based on the modified linear elastic fracture mechanics equation, the fatigue life of WC-Co cemented carbide was calculated. The calculated results of fatigue life agree well with the experimental results.