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Microstructure and Properties of Solid-State Additively Processed Alloy 600 Claddings on 304L Stainless Steel

Dalai, Biswajit
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1542724808933024

Abstract Details

2018, MS, University of Cincinnati, Engineering and Applied Science: Materials Science.
The microstructure and stress states bestowed by the manufacturing process administer the reliability and performance of each component in its final application. Additive Manufacturing (AM) is the trending process among all the innovative methods to produce uniform distribution of microstructure and properties in the constituent parts in a cost-effective manner. However, most of the fusion based manufacturing techniques possess a drawback in the form of residual stresses developed during the processing stage. This demands for the development of more effective AM methods having the potential for near-net shape manufacturing of the parts with minimized residual stresses which has led to the inception of a novel solid-state AM process named “MELD”. This study investigated the microstructure and properties developed in the multi-layer Alloy 600 deposit on 304L stainless steel manufactured by MELD process. Unlike other fusion based AM processes, MELD showed a compressive residual stress (~ -380 MPa) on the surface of the deposited material. The average hardness of the deposit (~ 3.29 GPa) was comparable with that of Alloy 600 manufactured by other AM processes. Additionally, a localized increase in the hardness could be observed at the interfaces between two subsequent layers which was attributed to the grain refinement resulting from dynamic recrystallization in the interfacial areas during the MELD process. Large amount of carbide precipitates formed during the recrystallization at the interface restricted the grains size by pinning them together. High temperature in areas away from interface caused dissolution of carbides leading to grain coarsening. This trend of grains size and carbide precipitates was repeated in each of the deposited layers. The point and space group of the carbide precipitate was determined from TEM analysis. The deposit possessed very low dislocation density and hence low plasticity. Though, the distribution of sub-grains and low angle boundaries followed a particular pattern in all the layers. A very strong texture was exhibited by the as-MELD processed deposit. It also displayed substantially higher tensile properties than other solid-state process counterparts. Advanced mechanical surface treatments were performed to develop plastic strains in the near surface region of the material. The effects of LSP could be observed to a much deeper extent. High compressive residual stresses of -1400 MPa and -900 MPa were measured in case of UNSM and LSP, respectively. UNSM increased the near surface hardness to 4.92 GPa, whereas, LSP increased the value to 4.3 GPa. The as-MELD processed Alloy 600 was annealed at 400°, 500°, 600° and 700° C each for 2 hours. The grains size distribution of annealed material followed the same pattern exhibited by the as-MELD processed material. Annealing at 400° and 500° C did not have much effects on the microstructural features. Though, the carbides that remained dissolved inside the matrix during the MELD processing, seemed to have reappeared when the material was annealed at 600° and 700° C. The carbides reduced the size of grains by pinning them. But the microstructural analysis could not explain the variation in the hardness of the annealed material.
Vijay Vasuedevan, Ph.D. (Committee Chair)
Ashley Pazy Puenta, Ph.D. (Committee Member)
Matthew Steiner, Ph.D. (Committee Member)
106 p.
Materials Science
MELD; Characterization; EBSD; Mechanical properties; Surface treatments; Heat treatment

Recommended Citations

Citations

  • Dalai, B. (2018). Microstructure and Properties of Solid-State Additively Processed Alloy 600 Claddings on 304L Stainless Steel [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1542724808933024

    APA Style (7th edition)

  • Dalai, Biswajit. Microstructure and Properties of Solid-State Additively Processed Alloy 600 Claddings on 304L Stainless Steel. 2018. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1542724808933024.

    MLA Style (8th edition)

  • Dalai, Biswajit. "Microstructure and Properties of Solid-State Additively Processed Alloy 600 Claddings on 304L Stainless Steel." Master's thesis, University of Cincinnati, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1542724808933024

    Chicago Manual of Style (17th edition)

ucin1542724808933024
255
© 2018, some rights reserved.Creative Commons License Microstructure and Properties of Solid-State Additively Processed Alloy 600 Claddings on 304L Stainless Steel by Biswajit Dalai is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Cincinnati and OhioLINK.