Date of Award

1-1-2017

Document Type

Masters Thesis

Degree Name

M.S.

Organizational Unit

Daniel Felix Ritchie School of Engineering and Computer Science

First Advisor

Maciej Kumosa, Ph.D.

Second Advisor

Brian Majestic

Third Advisor

Yun Bo Yi

Keywords

Additive manufacturing, Computer-aided design software, Finite elemental analysis

Abstract

Powder-based metal in additive manufacturing (AM) is advantageous for rapid prototyping of parts and components, with the benefit of reusing powder to reduce production costs. A common driver in the aerospace industry is free-form complex geometries which can be created using CAD software to optimize specifications with strength-to-weight ratios in components. Weight optimization of aircraft components using additive manufacturing reduces material, which significantly reduces production cost in comparison to cast and wrought metallic products. Large biomedical and aerospace industries heavily invest in feedstock metal powders that have low density under structural stresses and high temperatures, resulting in superior resistance to corrosion in extreme environments. The high strength-to-weight ratio material with long- term cost affordability obtained by AM process results in cost-efficiency of the Ti-6Al- 4V powder by recycling unspent powder material. However, while efficient, the recycling of titanium (Ti) powder in additive manufacturing results in micro-particle characterization, chemical, and mechanical changes due to indirect and direct environmental extremes. Direct exposure to high thermal heat during the electron beam melting (EBM) process after powder reclaiming can result in particle microstructure and chemical variations. Initial assessments of oxygen (O) wt% in bulk powder material was subsequently selected for further investigation as a characteristic for decline in mechanical properties of consolidated materials. A preliminary analysis of virgin, 5x-recycled, and artificially highly oxidized Ti-6Al-4V powder was conducted using Charpy impact testing on consolidated specimens from each wt% O in the bulk powder batches, and finite elemental analysis (FEA) to understand the build defect effect found in solidified Ti-6Al-4V material.

Publication Statement

Copyright is held by the author. User is responsible for all copyright compliance.

Rights Holder

Edward Patton Clark

Provenance

Received from ProQuest

File Format

application/pdf

Language

en

File Size

81 p.

Discipline

Materials Science, Mechanical Engineering

Download



Share

COinS