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Abstract：
In order to achieve the non-destructive testing and quality evaluation of stainless-steel resistance spot welding (RSW) joints, a portable ultrasonic spiral C-scan testing instrument was developed based on the principle of ultrasonic pulse reflection. A mathematical model for the quality evaluation of RSW joints was established, and the centroid of the ultrasonic C-scan image in the nugget zone of the RSW was determined based on the principle of static moment. The longest and shortest axes passing through the centroid in the image were extracted, and the ratio of the longest axis to the shortest axis (RLS) factor and the average of axis (AOA) factor were calculated, respectively, to evaluate the quality of the joint. To study the effectiveness of the detection results, tensile tests, and stereo analysis were conducted on the solder joints after sampling. The results indicate that this detection method can realize online detection and significantly improve the detection efficiency; the detection value of internal defect size is close to the true value with an error of 0.1 mm; the combination of RLS and AOA factors can be used to evaluate the mechanical properties of RSW joints. This technology can be used to solve the NDT, evaluate problems of RSW joints, and realize engineering applications.
摘要：
为了实现不锈钢电阻点焊(RSW)接头的无损检测和质量评定,基于超声脉冲反射原理，研制了便携式螺旋C扫描超声检测仪。建立了RSW接头质量评价的数学模型,基于静矩原理确定了RSW熔核区域的超声C扫描图像的质心。提取图像中通过质心的最长轴和最短轴，并计算了最长轴与最短轴之比(RLS)因子和轴平均值(AOA)因子,分别,评估接头的质量。为了研究检测结果的有效性，拉伸试验,取样后对焊点进行立体分析。结果表明,该检测方法能够实现在线检测,显著提高了检测效率;内部缺陷尺寸的检测值接近真实值,误差为0.1mm;RLS和AOA因子的组合可用于评价RSW接头的力学性能。这项技术可以用来解决无损检测，评估RSW接头的问题，并实现工程应用。
