Critical Comparison of Spherical Microindentation, Small Punch Test, and Uniaxial Tensile Testing for Selective Laser Melted Inconel 718

Abstract

Standardized mechanical tests have become one of the central bottlenecks in the efficient and cost-effective exploration of the process space in advanced manufacturing processes such as additive manufacturing (AM). This paper presents a critical comparison of the relative advantages and disadvantages between emergent high-throughput mechanical test protocols, specifically, spherical microindentation and small punch test, and standardized tension tests. The critical comparison considers the effectiveness and viability of the testing protocols to rapidly screen stress-strain data and mechanical properties of candidate AM-processed metal specimens. These comparisons were performed on samples of Inconel 718 produced by selective laser melting (SLM). Modulus, yield strength, and ultimate tensile strength were evaluated, and the combination of high-throughput mechanical test protocols displayed results consistent with standard tension tests. This study shows that high-throughput mechanical test protocols can successfully produce reliable stress-strain data using significantly smaller material volume and reduced labor compared to the standardized tension tests.