Date of Award

December 2019

Document Type


Degree Name

Master of Science (MS)


Mechanical Engineering

Committee Member

Garrett J Pataky

Committee Member

Huijuan Zhao

Committee Member

Xin Zhao


Additive manufacturing (AM) is becoming increasingly popular in the automotive, aerospace, energy and healthcare industries. Standards for critical defect sizes and porosity levels in AM materials have not been established. A critical porosity manufactured defect relationship which can qualify components for safe use needs to be developed. Defects including a quarter crack, an internal void, and a through-hole were intentionally manufactured into SS 316L and AlSi10Mg AM tubular tensile specimens to investigate and improve the understanding of the ductility-defect-porosity relationship of AM Metals. SS 316L and AlSi10Mg compression specimens were tested from different build heights and locations on the build plate to explore the effects of spatial location on the material properties. Thin single edge notch tensile fracture toughness specimens with AM notch and diamond saw notch were studied to investigate the apparent fracture toughness of thin AM specimens. Levels of porosity were introduced by reduced laser power in all the AlSi10Mg specimens. This study helps define the relationship between defects, porosity, and ductility of AM SS 316L and AlSi10Mg and compares this relationship to conventional metals. From the results of this study, AM SS 316L and AM AlSi10Mg follow conventional knowledge about stress concentration and ductility for metals.

There was no significant difference in fracture toughness between the AM and diamond saw notch in the fracture toughness specimens. The SS 316L compression specimens closer to the build plate had increased material properties while the AlSi10Mg compression specimens had similar material properties throughout. The material properties of the SS 316L and AlSi10Mg compression specimens varied by the build plate location.

Geometric defects decreased the ductility and strength for all the tubular tensile specimens. With a significant increase in porosity, the mechanical behavior started to be dominated by the porosity over the intentionally manufactured geometric defects. The mechanical behavior of the ductile SS 316L tubular specimens was driven by the reduction in the cross-sectional area while the more brittle AlSi10Mg was driven by stress concentrations. From this study, AM SS 316L and AlSi10Mg produced by selective laser melting had similar mechanical behavior to traditional ductile and brittle metals.



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