Evaluation of Weld Defects in Stainless Steel 316L Pipe Using Guided Wave

Abstract Stainless steel is a popular structural materials for liquid-hydrogen storage containers and pipingcomponents for transporting high-temperature fluids because of its superior material properties such as high strengthand high corrosion resistance at elevated temperatures. In general, tungsten inert gas (TIG) arc welding is used forbonding stainless steel. However, it is often reported that the thermal fatigue cracks or initial defects in stainlesssteel after welding decreases the reliability of the material. The objective of this paper is to clarify the characteristicsof ultrasonic guided wave propagation in relation to a change in the initial crack length in the welding zone ofstainless steel. For this purpose, three specimens with different artificial defects of 5 mm, 10 mm, and 20 mm instainless steel welds were prepared. By considering the thickness of s stainless steel pipe, special attention was givento both the L(0,1) mode and L(0,2) mode in this study. It was clearly found that the L(0,2) mode was moresensitive to defects than the L(0,1) mode. Based on the results of the L(0,1) and L(0,2) mode analyses, themagnitude ratio of the two modes was more effective than studying each mode when evaluating defects near thewelded zone of stainless steel because of its linear relationship with the length of the artificial defect.