镍基高温合金疲劳多裂纹扩展规律研究

采用光滑单边缺口小裂纹试样模拟了多裂纹的扩展情况,利用复型技术和光学显微镜观测了裂纹形态演化全过程,并初步分析了高温疲劳多裂纹的演化规律.结果表明:应力集中条件下的高温疲劳裂纹扩展主要是单裂系统破坏,随着温度升高,裂纹逐渐变为多裂系统;提高应力水平或升高温度,缺口表面典型区域萌生的小裂纹条数都将增多,平均裂纹长度都有所增大.

Research on Multi-Crack Propagation Regularity of High Temperature Fatigue

The small crack of a smooth single-edge notched specimen is adopted to simulate the multi-crack propagation situation. The complex technology and optical microscope are used to observe the whole process of the crack shape evolution. A preliminary analysis of the evolution regularity of high temperature fatigue crack is presented. It turns out that high temperature fatigue crack growth is a destruction of single split system under the conditions of stress concentration, and the crack gradually turns into multi-split system with the increasing temperature. The number of small cracks will increase in typical region of the gap surface if the level of stress or temperature is elevated, and the average crack length has increased.