Mechanical Engineering ETDs

Publication Date

Fall 11-7-2019

Abstract

Additive manufacturing allows for the development of complex geometrical designs that may otherwise be impossible to fabricate through common methods. This advantage has opened the door to a new testing method capable of rapid and efficient material property characterization and qualification. The technique exhibits how 100’s of sub-size tensile bars can be tested to show an inherent statistical variation of materials produced by laser powder bed fusion. The testing technique presented is used to evaluate various heat treatments of the nickel super-alloy Inconel 625 and the aluminum alloy AlSi10Mg after stress relief annealing. Statistical analysis using 3-parameter Weibull distributions is used to determine low-probably extreme values of both material’s mechanical properties. Abnormally low ductility values of hot isostatic pressed Inconel 625 are determined to be due to the presence of large carbides along grain boundaries, characterized by electron dispersive spectroscopy (EDS). Incorrect processing parameters lead to the formation of lack of fusion voids in the Al-alloy, significantly reducing the effective load-bearing cross-sectional and triggering premature failure.

Degree Name

Mechanical Engineering

Level of Degree

Masters

Department Name

Mechanical Engineering

First Committee Member (Chair)

Dr. Yu-Lin Shen

Second Committee Member

Dr. Tariq Khraishi

Third Committee Member

Dr. Jay Carroll

Document Type

Thesis

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