利用半高宽分析铝合金X射线法应力测试工艺

文中采用X射线法测试6061-T6铝合金焊接接头残余应力，为探究合理的应力测试工艺方案，对预置应力的等强梁进行X射线应力测试，测试过程中先后增加准直器直径和摇摆角，以衍射曲线半高宽表征衍射晶粒群微观应变，研究在准直器直径和摇摆角增加时衍射晶粒群微观应变均匀性的变化，对材料进行取向成像分析，并对比在晶粒择优取向强弱不同的两个区间内应力测试的结果. 结果表明，应力测试精度与晶粒择优取向的强弱相关，在晶粒择优取向较强的空间范围内，采用大于1°的摇摆角时，小角度晶界附近的相邻亚晶都能够参与衍射，从而使衍射晶粒群微观应变趋于均匀，因此X射线应力测试精度较高，在d = 2 ~ 4 mm范围内，增加准直器直径d可增加衍射晶粒数目，但对衍射晶粒群微观应变均匀性及应力测试精度的影响不大.

X-ray stress measurement process of aluminum alloy by analysis of the full width at half maxima

In this paper, X-ray method is used to test the residual stress of 6061-T6 aluminum alloy welded joints. In order to explore a reasonable stress measurement process, X-ray stress test is performed on the pre-stressed equal-strength beam. The diameter of the aperture and the oscillation angle are successively increased during the test. The full width at half maximum of the diffraction profile is used to characterize the microscopic strain of the diffracted grain group. The change in the uniformity of the microscopic strain of the diffracted grain group is analyzed when the aperture diameter and oscillation angle increase, as wll as performing orientation imaging analysis to compare the grain selection between two stress test scheme in different intervals of preferred orientation of the grains. The results show that the stress test accuracy is related to the strength of the preferred orientation of the grains. In the spatial range where the preferred orientation of the grains is strong, when oscillation angle greater than 1° is used, the adjacent sub-crystals near the small-angle grain boundary can participate in the diffraction, so that the microscopic strain of the diffracted crystal grain group tends to be uniform, so the X-ray stress measurement accuracy is higher, and when the aperture is added in the range of d = 2 ~ 4 mm, the increase of diameter d can increase the number of diffracted grains, but has little effect on the microscopic strain uniformity of the diffracted grain group and the accuracy of stress testing.