Ultrasonic C-scan Detection for Stainless Steel Spot Welds Based on Signal Analysis in Frequency Domain

Abstract

In this paper, ultrasonic C-scan detection is conducted on stainless steel spot welds, and C-scan images are obtained respectively through characteristic signal analysis in time domain and frequency domain. Cscan image of frequency domain characteristics signal, which is less affected by detecting conditions, can reflect the weld nugget morphology more truly. After C-scan image enhancement and edge detection processing, the dimension of spot weld nugget can be automatically obtained through equivalent diameter algorithm procedure. The dimension of nugget contains corona bond, and it is in good agreement with corona bond external diameter through metallographic measured value. So it can be taken as the reference to evaluate the quality of spot welds. Without the influence of corona bond, detection accuracy is very high. The error is less than 0.066 mm.

Quality Estimation in Small Scale Resistance Spot Welding of Titanium Alloy Based on Dynamic Electrical Signals

“…Martin et al 9) used the pattern recognition technique to classify ultrasonic oscillograms of welded joints. Liu et al 10) found that the ultrasonic C-scan image of frequency domain characteristics signal could be used for an accurate estimation of nugget dimension.…”

“…More attentions are now being paid to the non-destructive method. Non-destructive quality detection in traditional large scale resistance spot welding (LSRSW) is generally concentrated on the usage of electrode force, [1][2][3][4] electrode displacement, [5][6][7] ultrasonic signal, [8][9][10] dynamic resistance, [11][12][13][14] etc.…”

Detection of Periodic Defects Using Dual-Light Switching Lighting Method on the Surface of Thick Plates

“…Yong-Ju JEON, 1) Doo-chul CHOI, 1) Jong Pil YUN 2) and Sang Woo KIM 1) * specific type of defect and material.…”

“…In steel manufacturing conditions, many methods have been developed to improve the quality of steel and achieve automatic inspection. In this introduction, we briefly mention the various inspection techniques that have been developed for steel manufacturing environments, which include ultrasonic detection methods for stainless steel spot welds 2) and ductile iron, 3) quality monitoring using voltage signals for small-scale resistance spot welding, 4) 3D X-ray tomography inspection for fatigue in aluminum die castings, 5) and optical inspection techniques for slabs, 6,7) steel bar, 8,9) billets, 10) and silicon steel. 11) Although the several studies mentioned above have achieved good performance and can effectively detect their respective defects, it is difficult to apply them directly to defect detection in thick plate surfaces because each of these methods is optimized for a…”