Heterogeneous Deformation of As-Built Nickel Alloy 625 with Checkered Columnar Grains at Different Strain Rates (AMB2022-04).

Abstract

The Additive Manufacturing Benchmark Test Series (AM Bench) provides comprehensive measurement data for additive manufacturing (AM) simulations and modeling. As part of the primary AM Bench 2022 measurements, tensile testing at different strain rates and microstructural characterization on AM nickel alloy 625 (UNS N06625) in the as-built condition are performed. Tensile specimens are built with an X-Y alternating scan strategy on a commercial powder bed fusion machine and machined in accordance with ASTM E8 subsize specimen geometry. Each specimen is tested at a nominal strain rate of 10^-3 s^-1 or 10^-2 s^-1 on a servohydraulic material testing machine. Stereo digital image correlation (DIC) is used to report a virtual extensometer strain up to fracture and to show heterogeneous deformation with local crosshatch strain banding throughout the gauge section at both strain rates. Anisotropic deformation is also measured where the principal strains deviate from the isotropic strain path. Microstructural analysis using scanning electron microscopy (SEM) imaging and electron backscatter diffraction (EBSD) are performed to help illuminate the microstructural role in the anisotropy and heterogeneous deformation. Finally, nanoindentation followed by EBSD of the indents are performed to investigate the difference in the indentation response of different grain orientations and grain locations with respect to the laser track.