Influence of Sample Build Orientation and Thickness on the Microstructure and Mechanical Properties of Stainless Steel 316L Fabricated by Laser Powder Bed Fusion
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Author:
Al Hassanieh, Sultan
Graduate Program:
Materials Science and Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
May 23, 2024
Committee Members:
Allison Michelle Beese, Thesis Advisor/Co-Advisor Saurabh Basu, Committee Member John Mauro, Program Head/Chair Wesley Reinhart, Committee Member
The mechanical properties of micron to millimeter scale lattice structures are influenced by the
complex interplay between microstructural features and surface topography. This study aims to
investigate the contributions of grain morphology, grain orientation, and cross-sectional area
uncertainties associated with surface roughness on the mechanical properties of uniaxial tension
bars made of laser-beam powder fusion stainless steel 316L. Tensile samples with thicknesses of
0.25mm, 0.75mm, and 1.25mm were fabricated at angles of 0° and 40° from the build direction
and mechanically tested. Microstructural features, surface roughness, and geometric inaccuracies
were analyzed. It was found that the 0° samples exhibited higher yield strengths than the 40°
samples. Surface roughness significantly affected micrometer thickness measurements,
particularly for the 40° samples. To obtain accurate yield strength values, it was found that using
the smallest cross-section obtained via optical microscopy, rather than that obtained using
micrometers, is essential. Furthermore, the grain orientation in the 40° samples was found to be
more favorable for slip, resulting in the 0° samples having greater strength.
