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完成了6根表面经滚压处理的漏斗形圆棒试样疲劳短裂纹复型实验,结果表明其短裂纹行为表现出明显的微观结构短裂纹(MSC)和物理短裂纹(PSC)2阶段特征.在MSC阶段,由于不同微观结构障碍的阻碍,主导短裂纹出现2次较明显的扩展减速,进入PSC阶段后,随着主导短裂纹尺度的增长,该现象不再显著.与表面未经滚压的试样相比,在给定主导短裂纹尺度条件下,滚压试样的裂纹扩展速率低得多,这种差异在MSC阶段可达1个数量级.滚压试样平均疲劳寿命达到未滚压试样的6.4倍.表面滚压处理有效抑制了微裂纹的形核与合并,改善了局部微观结构条件,并推迟了MSC与PSC过渡阶段的到来,提高了材料的抗疲劳性能.对主导短裂纹尺度、疲劳寿命分数和有效短裂纹密度3种特征参量进行分析,确定了其良好假设分布和统计演化规律.
The experiment on fatigue short crack of 6 funnel-shaped round bar samples with rolling surface was completed. The results showed that the short crack behavior of the funnel-shaped round bar showed obvious microstructural short crack (MSC) and physical short crack (PSC) At the MSC stage, due to the obstruction of different microstructural obstacles, the dominant short-crack appeared two more obvious decelerations, and after entering the PSC stage, the phenomenon was not significant with the increase of dominant short-crack size. The crack propagation rate of the rolled specimens is much lower at given dominant short crack size, which can be up to one order of magnitude at the MSC stage, and the average fatigue life of the rolled specimens reaches Rolling the sample 6.4 times.The surface rolling process effectively inhibit the nucleation and merging of microcracks, improve the local microstructure conditions, and postponed the transition phase of MSC and PSC to improve the anti-fatigue properties of the material. The dominant short crack scale, the fatigue life fraction and the effective short crack density were analyzed. The good hypothetical distribution and statistical evolution rule were determined.