DZ125高温合金超高周疲劳裂纹萌生与扩展

裂纹的萌生与扩展是研究合金材料超高周疲劳行为的重要方面。本研究分析与探讨了温度和表面状态对DZ125合金的超高周疲劳裂纹萌生与扩展特征的影响。不同温度下,DZ125合金的超高周疲劳裂纹萌生位置和扩展方式不同。室温下,裂纹均沿表面起源,裂纹扩展以拉伸模式为主;700℃下,裂纹均沿亚表面起源,裂纹扩展以剪切模式为主。室温下,DZ125合金经激光冲击处理前后的超高周疲劳裂纹萌生位置和扩展方式均存在差异。经过激光冲击处理后,裂纹萌生于合金的内部孔洞缺陷,裂纹扩展完全以剪切模式进行。

Analysis on Ultra-high Cycle Fatigue Crack Initiation and Propagation Characteristics of DZ125 Superalloy

Crack initiation and propagation are important aspects of studying ultra-high cycle fatigue behavior of DZ125 superalloy. The analysis and discussion were carried on the effect of the temperature and surface status on the ultra-high cycle fatigue crack initiation and propagation character of DZ125 superalloy. The ultra-high cycle fatigue crack initiation position and propagation pattern of DZ125 superalloy vary with temperatures. All fatigue cracks initiated from the surface and propagated mainly in the tensile pattern at room temperature. All fatigue cracks initiated from the subsurface and propagated mainly in the shear pattern at 700 ℃. The ultra-high cycle fatigue crack initiation position and propagation pattern were different for DZ125 superalloy before and after laser shock processing at room temperature. The fatigue crack initiated from the cavities within the DZ125 superalloy and propagated entirely in the shear pattern.