Challenges in Standardizing Additive Manufacturing for Nuclear Components and Associated Material Testing II) a Statistical Approach to Material Specification Values and Procedures Qualification Methods for Additive Manufactured 316 L Stainless Steel

Additive Manufacturing (AM) is expected to play a significant role in various situations, such as the addition of high functionality to component by applying complex shapes that cannot be processed with conventional manufacturing methods, rationalization of production by applying of an integrated structure with decreasing parts number and realizing a quick parts supply in case of trouble. With the aim of standardization of Type316L stainless steel produced by laser powder bed fusion (L-PBF), material tests were conducted on AM materials that were fabricated by four different nuclear component manufacturers using their own independent conditions (different AM equipment, powder, process parameter and heat treatment) and evaluations included statistical analysis were performed based on the acquired data to investigate rational methods of procedure qualification and the appropriateness of referencing conventional material standard values. The tensile test samples were built throughout the entire building volume of the L-PBF equipment, and then subjected to heat treatment and specimen processing. The specimens were conducted on non-destructive testing and tensile testing was conducted at room temperature. As a result of the evaluation, it was confirmed that there was a difference in tensile properties at the upstream and downstream sides of the gas flow in the equipment. In addition, A-basis was calculated from the acquired data, and it was suggested that the AM material had characteristics equivalent to or better than the conventional Type 316L material standard values. Furthermore, the relationship between the number of tensile test specimens and A-basis was evaluated, and the standard requirements for tensile testing were examined to ensure material quality in the procedure qualification.