摘要
在不同的应力幅值下测试了7075-T651铝合金的疲劳寿命,拟合试验数据得到合金S-N曲线,估算疲劳极限为223MPa。用扫描电镜观察高低应力幅值下的疲劳试样断口,结果表明:合金的加工缺陷或粗大夹杂处往往为裂纹源,裂纹扩展伴随着小平面断裂的发生,高应力幅下疲劳裂纹扩展区出现犁沟和轮胎花样,而低应力幅下的疲劳裂纹扩展区中除有大量疲劳条带外,还出现了疲劳台阶和二次裂纹。合金的疲劳瞬断区则存在着撕裂棱与等轴韧窝。弥散分布的微小析出相对合金的疲劳性能有着积极的影响。
The fatigue life experiments of 7075-T651 aluminum alloy were conducted under different stress amplitude and S-N curves was gained from fitting the experimental data.An estimation of detailed fatigue limit result was 223MPa.The fractography of high stress amplitude and low stress amplitude using scanning microscope displayed that the crack initiation mostly derived from the interior flaw or inclusion,and crack propagation gone with the quasi-cleavage crack.The crack propagation regions under high stress amplitude was characterized by furrow and tyre patterns while lots of fatigue fringe together with the fatigue sidestep and secondary crack generated in the crack propagation regions of low stress amplitude.The tearing edge and equiaxial dimples existed in fatigue failure region of both high stress amplitude and low stress amplitude fracture surface.The bulky inclusion particles can be the crack initiation while dispersion of tiny precipitated phase has a positive influence on fatigue performance of 7075-T651 aluminum alloy.
出处
《航空材料学报》
EI
CAS
CSCD
北大核心
2010年第4期92-96,共5页
Journal of Aeronautical Materials
基金
国家863高技术研究项目(2007AA03Z548)
