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Study of the Formation and Dissolution of δ-ferrite During High Temperature Forging Processing of Austenitic, Martensitic and PH Stainless Steels

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 (Unpublished)

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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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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
de Souza Ciacco, Pedroped28@pitt.eduped280000-0002-6845-3992
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Thesis AdvisorGarcia, Calixto Isaaccigarcia@pitt.educigarcia
Committee MemberAbelev, Estaeabelev@pitt.edueabelev
Committee MemberTan, Sushengsut6@pitt.edusut6
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


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