Non-Destructive Evaluation of Artificial Defects in Additively Manufactured SS316L Stainless Steel Coupon

Abstract

Non-destructive evaluation (NDE) is widely used to ensure the quality and integrity of components. Various non-destructive testing methods have been developed and implemented to evaluate Additively manufactured (AM) products. Modern techniques in the AM production route enable the fabrication of complicated geometries with smaller lead time and minimum material wastage. Though this technique has many advantages; many bottlenecks are encountered during evaluation of the quality of products made in this route. The common defects noticed in the AM components are porosities, clusters of porosities, micro-cracks, lack of fusion and layer delamination. The detection and evaluation of defects plays a significant role prior to its application. Most of the existing NDT techniques are based on the analysis of electromagnetic radiation interaction with matter and the response of the sound or heat energy transmitted in the component to be tested. Different energy bands of the electromagnetic spectrum, ranging from gamma rays to radio waves, are used for quantitative and qualitative analysis in NDT applications. All conventional NDT techniques are not viable for the AM components owing to their complex geometrical and material characteristics. Radiography is suitable for the evaluation of the volumetric defects and Ultrasonic testing gives good results for the planar defects in the AM components. The defect detection capability of these techniques is based on the size and orientation of the defects with respect to the source beam direction. Radiography and Ultrasonic testing are experimentally tested for evaluating the artificial defects in SS316L stainless steel coupon made by laser powder bed fusion (LPBF) additive manufacturing technology. This paper presents and demonstrates the capabilities, advantages and limitations of radiography and ultrasonic testing techniques for the assessment of defects in SS316L coupon made by the AM route.