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Characterization of Microstructure and Mechanical Properties of Laser Powder Bed Fusion Processed Inconel 625 Alloy

Somasundaram, Aruneshwar
http://orcid.org/0000-0002-8097-1055
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1627658971938259

Abstract Details

2021, MS, University of Cincinnati, Engineering and Applied Science: Materials Science.
The Inconel 625 nickel-based superalloy is commonly used in aerospace and petrochemical industries for its excellent mechanical and corrosion properties in high temperature environments. In this study, a plate of Inconel 625 additively manufactured by a laser powder bed fusion process was subjected to microstructural characterization and mechanical testing post and prior to heat treatments. While this is a solid solution strengthened alloy, it also gains considerable strengthening through heat treatments by means of precipitating the favorable ?” secondary phase. However, during exposure to high temperatures, the precipitation regime for such a phase can coexist along with unfavorable phases; most notably, ? and other TCP phases. It is thus important to know the limits of such exposures and as well as the interrelationship between these phases. An aging heat treatment process between 600 ?C – 700 ?C can help study this material in its most important and frequently operated temperatures and can also help obtain a state with most beneficial mechanical properties. LPBF alloys, however, are subjected to rapid solidification during manufacturing and can possess considerably high amounts of residual stresses which can alter both, the microstructure and the mechanical properties. This requires a comparison study with similarly treated wrought counterpart material in order to assess the material’s feasibility for additive manufacturing. By characterizing the material using SEM, TEM and XRD, it was seen that the as-LPBF material possessed an epitaxial microstructure with a high concentration of dislocation cells, and which is seen as a major factor in enhancing its mechanical properties at room temperatures to be comparable to the heat-treated wrought alloy. With further aging heat treatments, by following a solution treatment and without one, it was seen that the material performed considerably better without recrystallization of its LPBF microstructure in room temperature mechanical testing. The as-LPBF material showed an increase in yield strength by nearly 250 MPa and was less than 50 MPa short of the aged wrought alloy with highest room temperature properties. Similarly, the directly aged LPBF material showed an increase of nearly 150 MPa in yield strength from the latter. It was noticed that the reason for the appreciable differences in properties exhibited are due to the manifestation of the dislocation cells and an indirect or a speculated direct resultant slower precipitation kinetics in the LPBF microstructure.
Vijay Vasudevan, Ph.D. (Committee Chair)
Yao Fu, Ph.D. (Committee Member)
Ashley Paz y Puente, Ph.D. (Committee Member)
97 p.
Materials Science
IN625; Alloy 625; Inconel 625; LPBF; Additive manufacturing; Precipitation

Recommended Citations

Citations

  • Somasundaram, A. (2021). Characterization of Microstructure and Mechanical Properties of Laser Powder Bed Fusion Processed Inconel 625 Alloy [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1627658971938259

    APA Style (7th edition)

  • Somasundaram, Aruneshwar. Characterization of Microstructure and Mechanical Properties of Laser Powder Bed Fusion Processed Inconel 625 Alloy. 2021. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1627658971938259.

    MLA Style (8th edition)

  • Somasundaram, Aruneshwar. "Characterization of Microstructure and Mechanical Properties of Laser Powder Bed Fusion Processed Inconel 625 Alloy." Master's thesis, University of Cincinnati, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1627658971938259

    Chicago Manual of Style (17th edition)

ucin1627658971938259
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