Characterizing the tensile behavior of additively manufactured metals at high temperatures using digital image correlation

In this work, the tensile behavior of conventionally and additively manufactured nickel-based (Inconel 625) and titanium-based (Ti-6Al-4V) alloys are examined when subjected to elevated temperatures. The additively manufactured materials were fabricated using the Laser Powder Bed Fusion technique. Uniaxial tensile experiments were conducted at room temperature and different temperatures ranging from 300 to 750°C while utilizing stereoscopic Digital Image Correlation (stereo-DIC) techniques to measure the strain field. The functionality of the stereo-DIC technique was validated by performing the same experiments on flat and curved surfaces, which yielded similar results. The goal of this thesis is to relate the measured thermomechanical properties to the different build orientations, manufacturing or machining methods, and the metal's microstructural features observed using the Scanning Electron Microscope. Conventionally manufactured Ti-6Al-4V exhibited higher yield strength, while Inconel 625 showed a higher tolerance to thermal loading. Heat-treated additively manufactured Ti-6Al-4V demonstrated a notable decrease in strength yet higher failure strains. The build orientations influenced the material behavior, displaying higher yield stresses, particularly at a 45° angle in samples cut from plates, while directly printed samples showed varied strengths across different orientations. A comparison of the tensile behavior of these two sample types revealed significant variance. The reduced tensile strength in directly printed samples is most likely associated with structural defects, such as voids and partially or fully unmelted powder particles, decreasing susceptibility to mechanical stresses and failure strains.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Aerospace Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2023

Author dc:creator

• Funck, Elisabeth

Contributors dc:contributor

• Lambros, John

• Additively Manufactured Metals
• Digital Image Correlation
• Thermomechanical Testing

Statement dc:rights

• Copyright 2023 Elisabeth Funck

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/122051

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F122051