CuCrZr铜合金高温阶梯疲劳与循环塑性行为研究

Study on Step Fatigue and Cyclic Plastic Behavior of CuCrZr Copper Alloy at High Temperature

摘要:

本文对CuCrZr铜合金在300℃和400℃开展了阶梯疲劳试验研究，从循环应变幅、平均应变、平均应变率和能量耗散率等方面研究其循环塑性行为。研究发现，CuCrZr铜合金的循环软硬化特征以及棘轮效应受到温度与循环应力的共同作用，温度越高，更易发生循环软化现象，同时棘轮效应也更加显著。基于对CuCrZr铜合金高温拉伸断裂能与高温阶梯疲劳总耗散能的对比发现，两者均与温度相关，因此将高温拉伸断裂能作为温度补偿参数，提出了一种基于能量法的线性损伤疲劳寿命预测模型，对CuCrZr铜合金高温阶梯疲劳寿命进行了预测。最后，基于断口分析分析了CuCrZr铜合金与温度相关的失效机理：在较低的温度下容易发生疲劳裂纹失效，而随着温度的升高，更易发生棘轮应变累积的韧性失效。

Abstract:

In this paper, the step fatigue test of CuCrZr copper alloy at 300°C and 400°C was carried out, and the cyclic plasticity behavior was studied from the aspects of cyclic strain amplitude, average strain, average strain rate and energy dissipation rate. It is found that the cyclic soft hardening characteristics of CuCrZr copper alloy and the ratchet effect are affected by the combination of temperature and cyclic stress, and the higher the temperature, the more prone to cyclic softening, and the ratchet effect is more significant. Based on the comparison between the high temperature tensile fracture energy of CuCrZr copper alloy and the total dissipative energy of high temperature ladder fatigue, both are related to temperature, so the high temperature tensile fracture energy is used as a temperature compensation parameter, and a linear damage fatigue life prediction model based on energy method is proposed, and the fatigue life of CuCrZr copper alloy is predicted. Finally, the temperature-related failure mechanism of CuCrZr copper alloy is analyzed based on fracture analysis: fatigue crack failure is prone to occur at lower temperatures, and with the increase of temperature, the ductility failure accumulated by ratchet strain is more likely.