Date of Award

2022

Publisher

North Dakota State University

Document Type

Thesis

Degree Awarded

Master of Science (MS)

Program

Civil Engineering

Department

Civil, Construction, and Environmental Engineering

College

Engineering

Faculty Advisor

Yellavajjala, Ravi Kiran

Description

Additive manufacturing provides exceptional geometrical freedom to the designers and enables the production of parts that cannot be made through subtractive processes. Defects in additively manufactured (AM) metals are detrimental to the manufactured components. This study aims to understand the fracture initiation mechanism in as-built AM 17-4 stainless steel. Micro-computed tomography (micro-CT) analysis was conducted on the undeformed and fractured unnotched and notched specimens to characterize the defects in the as-printed specimens before and after deformation. The micro-CT analysis showed that the initial void count and volume fraction increased after the deformation indicating new void nucleation and dilation of voids. Furthermore, coalesced void colonies were noticed in the fractured specimens in the vicinity of the fracture surface. Evidence for void nucleation, dilation, and coalescence indicates ductile fracture to be the fracture initiation mechanism in AM 17-4 steel.

Rights

NDSU policy 190.6.2

Rights Link

https://www.ndsu.edu/fileadmin/policy/190.pdf

Handle Identifier

https://hdl.handle.net/10365/33293

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