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Quantitative Determination of Residual Stress on Additively Manufactured Ti-6Al-4V

Ferraro, Mercedes M
http://rave.ohiolink.edu/etdc/view?acc_num=ysu152640278957619

Abstract Details

2018, Master of Science in Engineering, Youngstown State University, Department of Mechanical, Industrial and Manufacturing Engineering.
Additive manufacturing (AM) is a method to build a three-dimensional part through the layering of material. One category of AM, Direct Energy Deposition (DED), is commonly used with the titanium alloy, Ti-6Al-4V, and has shown to be useful for aerospace, transportation, and biomedical applications. However, the DED process induces anisotropic material properties due to the nonuniform temperature distribution, which causes residual stresses. In addition, when handling titanium and its alloys, the processing history and post-heat treatment greatly influence the microstructure, residual stresses, and mechanical properties. Previous research has been done to investigate the residual stresses by methods such as X-ray diffraction, contour methods, and finite element simulations. However, a less established technique for determining the residual stresses is through nanoindentation. Nanoindentation is the use of instrumented indentation to determine the mechanical behavior and properties of a small volume based on the load versus depth results. By applying nanoindentation techniques to a DED Ti-6Al-4V, it was found that the nanoindentation results varied based on the cross-sectional height of the sample. The reason for this occurrence was believed to be due to the microstructure and the existence of residual stresses. The nanoindentation results were then used to quantify the residual stresses present in the DED Ti-6Al-4V part using the basic methodology of Suresh and Giannakopoulos. Similar to the nanoindentation hardness and elastic modulus results determined, the residual stresses also showed an increasing trend when increasing in height along the cross-section. More specifically, as the height along the build direction increased, the residual stresses present increased in compressive behavior. However, future work is required to verify the validity of the Suresh model and its application to DED Ti-6Al-4V. Ultimately, by understanding the material characteristics of this part, it would help to further enhance the structural integrity of AM parts.
Jae Joong Ryu, PhD (Advisor)
Hazel Marie, PhD (Committee Member)
C. Virgil Solomon, PhD (Committee Member)
147 p.
Materials Science; Mechanical Engineering; Nanoscience
Additive Manufacturing; Direct Energy Deposition; Nanoindentation; Residual Stress; Ti-6Al-4V

Recommended Citations

Citations

  • Ferraro, M. M. (2018). Quantitative Determination of Residual Stress on Additively Manufactured Ti-6Al-4V [Master's thesis, Youngstown State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ysu152640278957619

    APA Style (7th edition)

  • Ferraro, Mercedes. Quantitative Determination of Residual Stress on Additively Manufactured Ti-6Al-4V. 2018. Youngstown State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ysu152640278957619.

    MLA Style (8th edition)

  • Ferraro, Mercedes. "Quantitative Determination of Residual Stress on Additively Manufactured Ti-6Al-4V." Master's thesis, Youngstown State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ysu152640278957619

    Chicago Manual of Style (17th edition)

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This open access ETD is published by Youngstown State University and OhioLINK.