7050铝合金二维超声滚压加工残余应力场研究

目的研究二维超声滚压后7050铝合金残余应力场的形成过程和表层残余应力的分布规律。方法利用有限元软件模拟二维超声滚压加工,分析残余应力场的形成过程及表层残余应力的分布规律;采用正交试验方法进行7050铝合金二维超声滚压加工试验,研究工艺参数对表面残余应力的影响规律,并与有限元分析结果相对比,验证有限元模拟的合理性。结果在二维超声滚压加工过程中,7050铝合金表层材料应力随时间先减小后增大,最后趋于稳定,形成残余应力。残余压应力沿滚压深度方向先增大后减小,再转化为残余拉应力。残余压应力层厚度约为1.05 mm,最大残余压应力值约为285 MPa。在相同的工艺参数下,有限元分析结果与试验结果基本吻合。静压力对表面残余应力的形成影响最大,表面残余压应力随静压力的增大而增大。结论二维超声滚压加工使7050铝合金表面发生剧烈的塑性变形,并形成一定深度的残余压应力。铝合金表面残余压应力随静压力的增大而增大,而与转速和进给量无关。

Residual Stress Field in the Process of 2D Ultrasonic Rolling 7050 Aluminum Alloy

The work aims to study formation process of residual stress fields and distribution law of surface residual stress of 7050 aluminum alloy after 2D ultrasonic rolling. Finite element software was used to simulate the process of 2D ultrasonic rolling, so as to analyze the formation process of residual stress fields and distribution law of the surface residual stress. Orthogonal experiment was designed to perform 2D ultrasonic rolling test to the 7050 aluminum alloy, so as to study the effect law of process parameters on surface residual stress. Test results were compared with finite element analysis results to validate reasonability of the finite element simulation. During the process of 2D ultrasonic rolling, surface material stress of the 7050 aluminum alloy first decreased and then increased, and finally tended to be stable, and residual stress formed; the residual compressive stress first increased and then decreased in the direction of rolling depth, and later translated into residual tensile stress; the thickness of residual compressive stress layer was about 1.05 mm, and the maximum residual compressive stress was 285 MPa. Provided with identical process parameters, the results obtained from finite element analysis were nearly consistent with the test results. Static pressure had the greatest influence on formation of residual stress, and the surface residual compressive stress increased as the static pressure increased. Severe plastic deformation occurs on the surface of 7050 aluminum alloy as a result of 2D ultrasonic rolling, and certain depth of residual compressive stress forms. The surface residual compressive stress of aluminum alloy increases along with the static pressure, but rotational speed and feed rate have little effect on the residual stress.