MECHANICAL CHARACTERIZATION OF AN ADDITIVELY MANUFACTURED METALLIC SUPER ALLOY USING MICRO TENSILE AND INSTRUMENTED INDENTATION TESTING

This study focuses on the mechanical characterization of an additively manufactured metallic superalloy, IN718, using micro tensile (MT) and instrumented indentation testing (IIT) techniques. Additive manufacturing (AM) or 3D printing enables complex geometries and unique microstructures in superalloys, which influence their mechanical behavior under stress. In addition, material directions in 3D-printed metals induce anisotropic mechanical properties that result from the layer-by-layer manufacturing process. To assess these properties, the MT tests are conducted along three major material directions: build, diagonal, and transverse. A digital image correlation (DIC) technique is implemented during the tests to measure the full-field strain on the specimen surface. These tests provide detailed insights into the alloy's strength, ductility, and strain behavior at small scales. Similarly, the nanoindentation tests are conducted by pressing a spherical and a three-sided diamond pyramid Berkovich indenter onto the material surface. These tests offer localized measurements of hardness and elastic modulus. Using two indenter geometries allows for a more systematic understanding of the material's mechanical properties across different scales and conditions, capturing both bulk and localized responses. Furthermore, the finite element (FE) simulations of the indentation tests are performed. The axisymmetric model is utilized to identify and optimize material parameters, while the 3D model is utilized to understand the detailed material behavior including localized stress and strain fields. The load-displacement predictions from the FE models are compared and matched with experimental results by adjusting the material parameters. The unified experimental and numerical approaches is executed to understand the alloy's mechanical response and capture the effects of AM-induced microstructural variations. This combined approach aids in understanding and optimizing the mechanical performance of superalloys produced through AM, supporting advancements in high-performance applications such as aerospace and energy sectors.