Publication Date

Summer 2024

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemical and Materials Engineering

Advisor

Ozgur Keles; Amir Armani; Raymond Yee

Abstract

Metal additive manufacturing (MAM) is a burgeoning industry. It is capable of manufacturing metal components with fine, intricate features and enables localized microstructural control. Due to its fine resolution and compatibility with common engineering alloys, selective laser melting (SLM) is one particular MAM process popular in academia and industry. The biomedical and aerospace industries have shown exceptional interest in the capabilities of SLM with the alloy Ti-6Al-4V. Because SLM Ti-6Al-4V components are aimed for use in critical applications, it is necessary to understand how SLM processing characteristics affect final part performance. One characteristic of SLM Ti-6Al- 4V that requires further study is the effect of print size on mechanical properties. With the capability to develop lightweight components with fine and complex features, it is critical to understand how size affects performance. In this work, the effect of size on mechanical properties was investigated for samples of twelve different sizes. Micro-computed tomography (μ-CT) was performed on some of the smallest samples to analyze porosity and pore characteristics. Tensile tests were undertaken to characterize how mechanical properties change with size. Scanning electron microscopy (SEM) was used to analyze fracture surfaces. It was found that as gauge area increased from 0.25 mm2 to 30 mm2 elastic modulus increased by 26%, yield strength decreased by 4%, tensile strength increased by 9%, and elongation after fracture increased by 163%.

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