DD6合金涡轮叶片裂纹失效分析

Crack Failure Analysis of Turbine Blade of DD6 Alloy

为了确定DD6合金涡轮叶片在工作过程中叶身排气窗处产生的裂纹的性质和产生原因,对裂纹叶片进行了外观检查、断口分析、成分分析和组织分析。结果表明:DD6合金涡轮叶片裂纹是叶片排气窗间隔墙内腔转接部位再结晶引起的疲劳开裂,再结晶晶粒产生于叶片生产过程中固溶处理之后;叶片其他排气窗间隔墙内腔表面存在小裂纹,是在叶片生产过程的再结晶检测工序中腐蚀液流进内腔侵蚀再结晶晶粒边界所致;并通过模拟试验再现了再结晶晶粒和小裂纹的产生。提出了增加叶片内腔再结晶检测控制、改进叶片排气窗结构或铸造工艺的建议。

In order to clarify the properties and causes of crack occurred on trailing edge of turbine blade of DD6 alloy,the appearance inspection,fracture analysis,composition analysis and microstructure analysis of the cracked blades were carried out.The result show that the crack of the turbine blade of DD6 alloy is fatigue cracking caused by recrystallization at the boundaries of the blade trailing edge partition wall,and the recrystallized grain is produced after the solid solution treatment during the blade production.There are small cracks on the inner surface of the other trailing edge partition wall of the blade,which is caused by the erosion of the recrystallized grain boundary by the flow of corrosion liquid into the inner cavity during the recrystallization detection process of the blade production process.The production of recrystallized grains and small cracks are reproduced by simulation test.The suggestions of increasing the detection and control of cavity recrystallization and improving the structure of trailing edge or casting process are put forward.