振动时效处理对7055-T7751铝合金疲劳性能的影响

对7055-T7751铝合金预拉伸板(预应变为1%~3%)进行振动时效处理,并在不同最大应力(300,350,400,500MPa)下进行疲劳试验,研究了振动时效处理对合金显微组织、显微硬度、表面残余应力和疲劳性能的影响。结果表明:振动时效处理对显微组织和显微硬度的影响很小,振动时效后的组织仍为轧制板材织构取向组织;振动时效处理后,合金中纵向和横向残余拉应力发生明显松弛,且纵向残余应力分布有所均化;振动时效处理明显提高了纵向和横向试样的疲劳性能,在最大应力350MPa条件下,纵向和横向试样的疲劳寿命分别提高了219.0%和29.1%,疲劳极限分别提高了9.9%和5.1%。

Effect of Vibratory Stress Relief Treatment on Fatigue Property of 7055-T7751 Aluminum Alloy

7055-T7751 aluminum alloy pre-stretching plate(pre-strains of 1%-3%)was subjected to vibratory stress relief treatment,and then to fatigue tests under different maximum stresses(300,350,400,500 MPa).The effects of vibratory stress relief treatment on microstructure,microhardness,surface residual stress and fatigue property of the alloy were studied.The results show that the vibratory stress relief treatment had little effect on the microstructure and microhardness;the microstructure after vibratory stress relief was still the texture orientation structure of the rolled plate.After the vibratory stress relief treatment,the longitudinal and transverse residual tensile stresses in the alloy were obviously relaxed,and the longitudinal residual stress distribution was homogenized.The vibratory stress relief treatment improved the fatigue performance of the longitudinal and transverse specimens significantly.Under the maximum stress of 350 MPa,the fatigue lives of the longitudinal and transverse specimens increased by 219.0% and 29.1%,and the fatigue limits were improved by 9.9% and 5.1%,respectively.