Challenges in Standardizing Additive Manufacturing for Nuclear Components and Associated Material Testing IV) Evaluation of Material Properties for Additively Manufactured Type 316L Stainless Steel

Additive Manufacturing (AM) presents a revolutionary potential to produce complex components that are challenging to fabricate through traditional methods such as machining, welding or casting, often requiring sophisticated skills and extensive knowledge. Four major Japanese nuclear power plant suppliers have collaboratively launched a national project supported of the Ministry of Economy, Trade and Industry (METI) together data on AM materials. This project consists of three steps: verification of qualification testing methods for AM material manufacturing processes, acquisition of basic material characteristic data for additive manufactured sample, and confirmation of product verification methods using mock-ups. In step 2 of this project, data was collected on the temperature dependence of the material properties of additive manufacturing samples made from 316L stainless steel using laser powder bed fusion (L-PBF) and laser wire energy deposition (LW-DED). L-PBF was produced using four different batches of powder, equipment, and post-heat treatment conditions. The evaluation samples underwent two types of post-heat treatments: solution annealing (SA) and hot isostatic pressing (HIP) combined with solution annealing (HIP+SA). For the LW-DED additive manufacturing samples, tests were conducted in two conditions: as-built and SA. The tests on material properties evaluated the mean coefficient of thermal expansion, Young’s modulus, Poisson’s ratio, and thermal conductivity. It has been confirmed that the temperature dependence of material properties shows the same trend even in samples manufactured in different batches. Differences in Young’s modulus and Poisson’s ratio were observed based on the manufacturing direction, but no significant differences were found in the mean coefficient of thermal expansion and thermal conductivity, indicating that they are largely unaffected by the manufacturing direction.