2397合金高周疲劳性能及裂纹萌生扩展行为

High-cycle fatigue properties and crack initiation and propagation behavior of 2397 alloy

摘要:

研究2397-T87铝锂合金的高周疲劳性能及裂纹萌生扩展行为。结果表明：在应力比R=0.1时，2397-T87铝锂合金L方向、LT方向和ST方向光滑试样（Kt=1.0）的疲劳寿命极限分别约为192 MPa，243 MPa和151 MPa；缺口试样（Kt=3.0）的疲劳寿命极限分别约为72 MPa，78MPa和70 MPa。其疲劳裂纹主要萌生于试样表面，以及氧化物、夹杂等脱落形成的空洞，Al（CuFeMn）第二相杂质粒子。驻留滑移带（PSB）和晶粒取向对其疲劳裂纹早期扩展有重要影响。

Abstract:

The high-cycle fatigue properties and crack initiation and propagation behavior of 2397-T87 Al-Li alloy were investigated. The results show that when the stress ratio R is 0.1, the fatigue limit of smooth specimens of 2397-T87 Al-Li alloy in the L orientation, LT orientation and ST orientation are about 192 MPa, 243 MPa and 151 MPa respectively. The fatigue limit of notch specimens in the L orientation, LT orientation and ST orientation are about 72 MPa, 78 MPa and 70 MPa respectively. Fatigue crack initiation of this alloy mainly occurred on the sample surface, with initiation from the defects caused by the oxides and inclusions, the Al(CuMnFe) secondary phases. Persistent slip bands (PSB) and grain orientation have important influence on fatigue crack propagation at early stage.