Facco, Giovanni Giuseppe
(2009)
EFFECT OF COOLING RATE AND COILING TEMPERATURE ON THE FINAL MICROSTRUCTURE OF HSLA STEELS AFTER HSM AND/OR LABORATORY TMP PROCESSING.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
Four different grades of High Strength Low Alloy Steels were investigated. This report presents an analysis of the effect that cooling rate and coiling temperature have on the final microstructure of these steels. First, a complete microstructural characterization of the as received hot band material was conducted with the aid of Optical Microscopy, Scanning and Transmission Electron Microscopy, and Electron Backscatter Diffraction-Image Quality analisys. Dilatometric studies to assess the transformation behavior of austenite under controlled continuous cooling conditions were conducted. The results provided the transformation temperatures for these grades. Finally the information gathered from the dilatometry was used to design a thermomechanical processing procedure where cooling rate and coiling temperature were varied and the effects studied. The results show that cooling rate has an important role in the final ferrite grain size, where in most cases samples cooled at 30 C/s to the coiling temperature showed grain refinement over those cooled at 10 C/s. The combination of the cooling rate and low coiling temperatures defined the transition from polygonal ferrite to acicular ferrite. A complete characterization of the final microstructures was carried out and the microstructural components were used to predict the yield stress value expected for a given processing condition.
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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Unpublished |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: |
25 September 2009 |
| Date Type: |
Completion |
| Defense Date: |
28 April 2009 |
| Approval Date: |
25 September 2009 |
| Submission Date: |
26 May 2009 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Materials Science and Engineering |
| Degree: |
MSMSE - Master of Science in Materials Science and Engineering |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Coiling Temperature; EBSD; High Strength Low Alloy; HSLA; HSM; Microstructure; SEM; Steel; TMP; Cooling Rate; TEM |
| Other ID: |
http://etd.library.pitt.edu/ETD/available/etd-05262009-135839/, etd-05262009-135839 |
| Date Deposited: |
10 Nov 2011 19:45 |
| Last Modified: |
15 Nov 2016 13:43 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/7956 |
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