摘要
本研究测量了Al 7075—T651铝合金的疲劳裂纹扩展率和中间△K疲劳载荷区间的疲劳条纹间距,对材料微观结构在疲劳裂纹扩展中的作用进行了量化分析,建立了剪切断裂机制和夹杂物断裂—韧窝形成机制引起裂纹扩展的实验方程。研究还发现了K_(max,o)和K'c两个转折点,低于K_(max,o),裂纹仅由剪切断裂机制引起;高于K'c,裂纹由夹杂物断裂—韧窝形成机制主导,在K_(max,o)和K'c之间,疲劳裂纹扩展由上述两者共同组成。
The fatigue crack growth rates and the striation spacings in A17075-T651 aluminium alloy were measured at intermediate ΔK region. A quantitative microstructural analysis of fatigue crack growth is made and the empirical relations between the growth rates caused by shear decohesion and by inclusion-fracture dimple formation and ΔK are obtained. Two transition points Kmax,o and K'c were found. Below the Kmax,o a crack grows by shear decohesion only. Above the K'c a crack grows by inclusion-fracture dimple-formation, Between Kmax,o and K'c, a fatigue crack grows by the conbination of both of these two mechanisms.
基金
美国Syracuse大学机械与航空航天工程系的George Sachs实验室进行的
由美国宇航局(NASA)提供资助
关键词
疲劳裂纹扩展
夹杂物
铝合金
fatigue crack growth Inclusion effect
striation spacing
microstructural analysis
