X射线衍射法测量铝合金残余应力及误差分析

Residual Stress in Aluminum Alloy Measured by X-ray Diffraction and Error Analysis

在介绍了X射线衍射法测量残余应力基本原理的基础上,以7075铝合金板材为实验对象,Photo公司的X射线衍射仪为实验仪器,采用不同的方向和衍射角对水域淬火后的7075铝板的表面残余应力进行测试,对测试结果进行处理并分析了应力产生的原因,提出了针对各种原因的解决方法。发现在单一方向上测量结果的线性和相关性在一端较好,另一端偏差较大,而相反方向时则相反。实验结果表明,从两个方向测定可减少应力测试误差;当测定值2θ的距离差平方和越小,自变量sin2ψ的间距越大,测试点越多且直线性越好,则应力测定误差越小;较长的曝光时间和合适的表面处理可以提高测试精度。

The principle of measuring residual stress was introduced by X-ray diffraction.Taking aluminum alloy 7075 plate as experiment object and Photo＇s X-ray diffraction apparatus as experiment instrument,the residual stress was measured with different orientation and diffraction angle,then the errors and reasons were analyzed by contrasting testing results.It is discovered that the linear measurement and relevance in one end is much better in a single direction,while it＇s contrary in the opposite direction.The results show that it＇s effective to decrease the error of measurement from two directions,the linear stress-measurement error is smaller when the numerical difference of 2θ is smaller.The greater the Sin2 ψ,the more the testing points,the better the linear.A longer exposure time and a suitable surface treatment can improve the testing precision.