焊接残余应力的非接触无损测量实验

Experiment for non-contact and nondestructive measurement of welding residual stress

焊接残余应力是降低焊接接头力学性能的主要因素之一,传统的残余应力测量多采用破坏性方法,如盲孔法,测量精度低、重复性差、人为影响因素多。X射线衍射法是非接触式无损的应力测量方法,测量精度高、数据稳定性好。学生采用X射线衍射法完成了焊接残余应力的测量实验,结果表明随着与焊缝距离的增大残余拉应力的峰值降低,热处理和超声波处理都能够有效地降低焊接残余拉应力,甚至能够把焊缝表面的残余拉应力转变为压应力。实验有助于学生了解焊接残余应力的基本分布规律,从而深刻理解焊接过程的特点,取得了较好的实验教学效果。

Welding residual stress is one of the main factors that reduce the mechanical properties of weld joint. Destructive methods such as blind-hole method are commonly applied in traditional meas- urement for residual stress measurement, with many defects such as low measuring accuracy and re- peatability and unavoidable artificial factors. X-ray diffraction method is a non-contact and nonde- structive stress measurement, with high measuring accuracy and good data stability. Measurement of welding residual stress experiments are completed by students with the help of the X-ray diffraction method. The results show that the peak value of welding residual tensile stress is reduced with the in- crease of the distance between the measurement point and weld center. Welding residual tensile stress can be effectively reduced with heat treatment and ultrasonic treatment, which can even turn the resid- ual tensile stress to compressive stress on the surface of the weld. The experiment can help students un- derstand the basic distribution of welding residual stress so as to understand the characteristics of the welding process, and desirable experiment teaching results have been achieved.