20钢焊接缺陷磁记忆信号分析

对含有焊接缺陷的试块进行磁记忆检测,研究了金属磁记忆检测技术对裂纹、气孔、未焊透、未熔合、夹渣缺陷的检出能力,对裂纹、气孔、未焊透、未熔合、夹渣区域的磁场强度梯度平均值H_ave、最大值H_max、磁场强度梯度曲线围成的面积S(H)、磁场强度梯度平均值K_ave、最大值K_max、磁场强度梯度曲线围成的面积S(K)进行计算,并与无缺陷区域的参数进行对比分析.结果表明,焊缝中裂纹、气孔、未焊透、未熔合、夹渣区域的K_ave,K_max,S(K)明显区别于无缺陷区域,可以准确判定焊接缺陷位置;焊接缺陷和焊接残余应力虽然都会导致磁记忆信号的变化,但是二者具有本质不同.

Analysis of magnetic memory signal of 20# steel welding defects

The test blocks with welding defects were detected by the method of metal magnetic memory, and the testing ability of the metal magnetic memory technology on welding defects including crack, porosity, incomplete penetration, lack of fusion, slag inclusion was studied. For the welding defects such as cracking, porosity, incomplete penetration, lack of fusion, slag inclusion in welded joints, their average value H_ave and the maximum value H_max of the magnetic field intensity, the area surrounded by the magnetic field intensity curve, the average value and maximum value of the magnetic field intensity gradient, the area surrounded by the magnetic field intensity gradient curve, were calculated and analyzed, respectively, which is also compared with the defect-free regions. The results show that、 of the welding defect are significantly different from parameters of the defect-free regions, whichcan accurately identify the location of welding defects. Whether it is a welding defect, or welding residual stress, itcan lead to changes of magnetic memory signal, but there are essential distinction between above two.