粉末高温合金FGH4099疲劳小裂纹扩展试验

Experimental Investigation on Small Crack Propagation Behaviors of Powder Metallurgy SuperalloyFGH4099

中文关键词:  粉末合金  FGH4099高温合金  疲劳小裂纹  裂纹萌生  裂纹扩展  航空发动机

英文关键词:powder metallurgy alloy  FGH4099 superalloy  small fatigue crack  crack initiation  crack propagation  aeroengine

中文摘要:

      为了解轮盘特征部位小裂纹萌生及演化扩展过程与应力特征、载荷环境条件、表面缺陷特征等因素的相关规律，基于 FGH4099合金涡轮盘轮缘结构特征设计特征模拟件，结合其典型的使用温度和载荷，开展了在高温条件下自然萌生疲劳小裂纹扩 展试验。通过疲劳中断试验和表面复型技术在不同温度和应力比条件下对结构模拟件的裂纹萌生和小裂纹扩展行为进行了观测 和分析。结果表明：试验温度升高能显著降低特征模拟件疲劳裂纹萌生寿命占比，对裂纹扩展至工程可检裂纹尺寸时的寿命占比 影响较小；缺口部位最大主应力位置和表面夹杂物位置是决定特征模拟件疲劳裂纹萌生位置的主要因素；当裂纹萌生机制或裂纹 萌生处缺口半径尺寸不同时，疲劳小裂纹扩展速率表现为不同变化趋势。

英文摘要:

      To understand the correlation of small crack initiation and propagation process with stress characteristics, loading condi? tions, and surface defects, a simulated component was designed based on FGH4099 powder turbine disk rim geometrical characteristics, combined with its typical service temperature and load, the natural initiation small fatigue crack tests were carried out under high- temperature conditions. The crack initiation and small crack propagation behaviors under different temperature and stress-ratio conditions were observed and analyzed through fatigue interruption tests and surface replication techniques. The results show that the increase of test temperature can significantly reduce the proportion of crack-initiation life of the simulated component, and has little effect on the life proportion of fatigue crack propagating to the engineering detectable crack size. The locations of maximum principal stress and surface inclusions are the main factors determining the crack initiation location of the simulated component. The small fatigue crack growth rate exhibits different trends with different crack initiation mechanisms or notch radius at crack initiation locations.