Henry D. Young, Ph.D. (Committee Co-Chair); Joy Gockel, Ph.D. (Committee Co-Chair); Onome Scott-Emuakpor, Ph.D. (Committee Member)
Master of Science in Materials Science and Engineering (MSMSE)
Additive Manufacturing (AM), particularly laser powder bed fusion, is being studied for use in critical component applications. Tensile and fatigue testing shows differences when built using different laser powers. However, when fabricated in an as-printed geometry, the gauge sections of the two specimens are different and experience different thermal behavior. This work explores microhardness, microstructure size, Niobium segregation, and porosity from samples made with varying laser power and different build geometry sizes representative of the gauge sections in the tensile and fatigue bars. Results show that microhardness varies spatially across the sample. Smaller diameter metallographic coupons (fatigue diameter) have a coarser microstructure and lower microhardness than the larger diameter (tensile diameter) when built using the same parameters. Therefore, the fatigue and tensile properties are not comparing the same material structure. Understanding the effect of build geometry on microstructure provides insight towards consistency in AM mechanical properties testing strategies.
Department or Program
Department of Mechanical and Materials Engineering
Year Degree Awarded
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