W18Cr4V刀具钢低周疲劳行为及寿命预测分析

Low Cycle Fatigue Behavior and Life Prediction of W18Cr4V Tool Steel

分别以室温与550℃高温环境对W18Cr4V刀具钢开展单轴低周疲劳测试,对比了不同温度下试样non-Masing行为变化情况,利用能量法实现了疲劳寿命的预测分析。研究结果表明当应变区间为1.2%时,初始循环阶段形成了最明显的硬化。在高温环境中位错更快发生湮灭,材料也更快进入循环软化的阶段,使得温度达到550℃时,材料表现出了更高软化率。达到1.2%的大应变程度时,材料形成显著non-Masing行为。当应变程度提高时,形成了更多的锯齿结构,逐渐提高应变幅值时,产生了更强的位错集体效应,加剧了锯齿屈服程度。低应变时形成了简单的波形结构,发生动态应变时效时产生了较小的热激活能;应变达到1.2%时,形成了复杂的波形,动态应变过程中产生了很大的热激活能。

Uniaxial low cycle fatigue tests were carried out on W18Cr4V aluminum alloy at room temperature and 550℃,respectively,the non-masing behavior of the samples at different temperatures was compared,and the fatigue life prediction analysis was realized by using energy method.The results show that the most obvious hardening occurs at the initial cycle stage when the strain range is 1.2%.In the high temperature environment,the dislocation annihilation occurs faster and the material enters the cycle softening stage faster,so that the material shows a higher softening rate when the temperature reaches 550℃.When the strain reaches 1.2%,the material forms significant non-masing behavior.As the strain level increases,more serrated structures are formed.When the strain amplitude is gradually increased,the collective effect of dislocation is stronger and the sawtooth yield degree is intensified.In the lower strain range,a simple wavy structure is formed,and a small thermal activation energy is generated when dynamic strain aging occurs.When the strain reaches 1.2%,complex waveforms are formed,and great thermal activation energy is generated in the dynamic strain process.