Duan, Junyu
(2016)
Influence of Composition and Thermomechanical Processing Conditions on the Microstructure and Properties of Hot Rolled Microalloyed Steels.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
This study investigated the effects of selected chemical compositions and processing conditions on the microstructures and mechanical properties of microalloyed hot rolled band. Also, the comparisons have been made between hot rolled band and QT steel. The microstructures of all the specimens were characterized by optical microscopy, scanning microscopy, electron back-scattered diffraction pattern techniques, and the stored energy was calculated by the subgrain method. The mechanical properties including microhardness, tensile and Charpy V-notch impact properties were measured. The relationship between microstructure and mechanical property behaviors has been made. The results show that vanadium can significantly improve strength at high coiling temperatures, but the effectiveness decreased with the lower coiling temperatures. Vanadium also played a very important role in tempering resistance. The relationship between the relative concentration of vanadium and nitrogen has been discussed. It showed that increasing concentration of nitrogen and decreasing concentration of aluminum would not help to improve the final strength and would increase the grain size. Coiling temperature is another important parameter in the hot rolling process since the OM, SEM and EBSD results showed that with different coiling temperatures, the microstructures and mechanical properties of the materials exhibited great difference. The experiment results confirmed the phase transformation predictions made by using the JmatPro thermo-kinetic software.
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| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
15 June 2016 |
| Date Type: |
Publication |
| Defense Date: |
25 March 2016 |
| Approval Date: |
15 June 2016 |
| Submission Date: |
28 March 2016 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
95 |
| 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: |
HSLA steels, Vanadium, Thermomechanical processing, Stored energy |
| Date Deposited: |
15 Jun 2016 13:38 |
| Last Modified: |
15 Nov 2016 14:32 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/27373 |
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