Electromagnetic Testing Of Three-Dimensional Residual Stress In Welding

Welding is one of the processes that combine metal or other shaping materials,and the residual stress generated by welding affects the performance of the component.How to quickly detect and get accurate residual stress is a problem that researchers at home and abroad need to solve.At present,whether it is X-ray,ultrasound,magnetic measurement,or other methods,it is a surface residual stress,which cannot directly detect the remnant stress in a certain depth inside the metal component.The performance of the component is the residual stress on the three dimensions,so it is particularly important to obtain the residual stress on the surface of the component and a certain depth.Therefore,the main work and innovation of this article are as follows:(1)The magnetic measuring instrument developed by the research group was subjected to stress correction,and the strain gauge method and magnetic measurement methods were used to test the equivalent cantilever beam,verifying the accuracy of the magnetic instrument in measuring stress;The stability of the magnetic measuring instrument was verified by measuring the stress of the same steel plate twice using a magnetic measuring instrument.(2)In order to accurately obtain the original stress distribution inside the Q235 steel plate,a saturated sodium chloride solution was used to conduct chemical corrosion peeling on the steel plate.After each layer of corrosion was completed,the stress on the surface of the steel plate was measured,and the corresponding stress measurement values were corrected to obtain the stress status of the layer before corrosion.By using this method,the internal stresses of welded and non welded steel plates were obtained,thereby obtaining the stress distribution from the surface to the interior of the steel plate,and constructing a three-dimensional stress field for both welded and non welded steel plates.(3)It is found that the internal stress level of the steel plate with welds is relatively high.Due to the influence of multi pass welding,the phenomenon of stress concentration occurs many times in the welds and Heat-affected zone,and the transformation of tensile stress and compressive stress occurs.The stress level inside the welded steel plate is relatively low and evenly distributed.Due to the flame cutting operation,there is a slightly higher stress at the edge of the steel plate,and the stress level in the middle layer of the steel plate is higher than that on the upper and lower surfaces.The research conclusion of this article suggests that using a combination of electrolytic corrosion method and magnetic method to measure residual stress can quickly obtain the three-dimensional stress of welded steel plate butt welded specimens;The welding process will introduce large residual stress,and the stress extreme value generally appears in the Heat-affected zone and weld zone;The two-dimensional and three-dimensional stress cloud maps drawn are intuitive and provide a reference for analyzing the residual stress patterns of welded components.The thesis has 55 figures,11 tables,and 102 references.