de Souza Ciacco, Pedro
(2023)
Study of the Formation and Dissolution of δ-ferrite During High Temperature Forging Processing of Austenitic, Martensitic and PH Stainless Steels.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
The present study develops a logical and novel approach to understand the formation and dissolution of δ-ferrite during high temperature forging processing of 15-5 PH, Jethete (154-M), and 304 L stainless steels. This new process proposes alternative routes to examine the dissolution kinetics behavior of δ-ferrite, creating an in-depth comprehension about the synergistic effect of chemical composition, reheating temperature, deformation temperature, amount of deformation (ɛ), and strain rate (έ). In addition, well-known conventional annealing heat treatments, based exclusively on time and temperature, acted as a parameter to be further compared with the new proposed technique. The introduction of deformation at high temperatures is expected to increase the kinetics of dissolution of δ-ferrite, consequently decreasing the total heat treatment time to fully dissolve this microconstituent. Combining time, temperature, and deformation, a forging process could be represented, while the effect of those forging strategies on the formation and dissolution behavior of δ-ferrite could be understood. As the dissolution starts to take place, chemical variations along the matrix and δ-ferrite could be noticed, mainly in terms of Chromium. Aiming the homogenization of the microstructure, the Cr content tends to be equalized, not showing discrepancies between the matrix and the δ-ferrite areas.
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Details
| Item Type: |
University of Pittsburgh ETD
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| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
13 June 2023 |
| Date Type: |
Publication |
| Defense Date: |
6 March 2023 |
| Approval Date: |
13 June 2023 |
| Submission Date: |
9 March 2023 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
101 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Materials Science and Engineering |
| Degree: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
δ-ferrite, Stainless Steels, Dissolution, Processing, Forging, Kinetics, Thermodynamics, Simulation |
| Date Deposited: |
13 Jun 2023 13:00 |
| Last Modified: |
13 Jun 2023 13:00 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/44265 |
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