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The role of Cr and Mo alloying element additions on the kinetics and effects of Upper Bainite formation in quench and tempered plate steels
Dissertation (MSc)--University of Pretoria, 2013.
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| Format: | Thesis |
| Language: | English |
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University of Pretoria
2014
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| _version_ | 1867613720496046080 |
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| access_status_str | Open Access |
| author2 | Stumpf, Waldo E. |
| author_browse | Stumpf, Waldo E. |
| author_facet | Stumpf, Waldo E. |
| collection | Thesis |
| dc_rights_str_mv | © 2013 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MSc)--University of Pretoria, 2013. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/33321 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:40:38.203Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2014 |
| publishDateRange | 2014 |
| publishDateSort | 2014 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/33321 The role of Cr and Mo alloying element additions on the kinetics and effects of Upper Bainite formation in quench and tempered plate steels Stumpf, Waldo E. Siyasiya, Charles Witness Leach, Lindsay Josephine Isothermal transformation Bainite Bainite Martensite structures Toughness Instrumented impact testing Dilatometry Isothermal transformation UCTD Dissertation (MSc)--University of Pretoria, 2013. The aim of the work presented was to investigate the effects of upper bainite on impact toughness in quench and tempered low alloy plate steels. The experimental research included construction of CCT diagrams by dilatometry, verification of phases by optical microscopy (OM), Vickers hardness, scanning electron microscopy (SEM), transmission electron microscopy (TEM) on precipitates extracted by carbon replica and by electrolytic means and finally impact testing of Charpy specimens with mixed bainite:martensite microstructures. Bainite was formed in High Chromium Low Molybdenum (HCrLMo) and in High Molybdenum Low Chromium (HMoLCr) steel samples by isothermal annealing within the bainite C-curve of the respective CCT diagrams. The isothermal kinetics of the upper bainite transformation was modelled with the Johnson Mehl Avrami Kolmogorov (JMAK) model. Avrami exponents of 1.4 and 1.3 were obtained for the HCrLMo and HMoLCr steels respectively which indicated linear growth with a considerable lengthening rate of laths and negligible thickening. The measurably slower growth kinetics in the HMoLCr steel as observed in the JMAK model and the higher hardenability with reference to its CCT diagram, suggested a strong Mo alloying element effect. The stronger effect of Mo compared to Cr was attributed to a solute drag like effect. The effect of upper bainite in a tempered martensitic matrix was investigated for the following amounts of bainite; 0%, 10%, 25%, 60%, 75%, 90% and 100%. The impact toughness of the mixed bainite:martensite samples was evaluated against the toughness of 100% bainite and 100% martensite. It was demonstrated that upper bainite reduces the total absorbed impact energy by an adverse effect on crack nucleation energy and crack propagation energy. gm2014 Materials Science and Metallurgical Engineering Unrestricted 2014-02-11T05:09:22Z 2014-02-11T05:09:22Z 2013-09-04 2013 Dissertation Leach, LJ 2013,The role of Cr and Mo alloying element additions on the kinetics and effects of Upper Bainite formation in quench and tempered plate steels, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/33321> E13/9/1008/gm http://hdl.handle.net/2263/33321 en © 2013 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Isothermal transformation Bainite Bainite Martensite structures Toughness Instrumented impact testing Dilatometry Isothermal transformation UCTD The role of Cr and Mo alloying element additions on the kinetics and effects of Upper Bainite formation in quench and tempered plate steels |
| title | The role of Cr and Mo alloying element additions on the kinetics and effects of Upper Bainite formation in quench and tempered plate steels |
| title_full | The role of Cr and Mo alloying element additions on the kinetics and effects of Upper Bainite formation in quench and tempered plate steels |
| title_fullStr | The role of Cr and Mo alloying element additions on the kinetics and effects of Upper Bainite formation in quench and tempered plate steels |
| title_full_unstemmed | The role of Cr and Mo alloying element additions on the kinetics and effects of Upper Bainite formation in quench and tempered plate steels |
| title_short | The role of Cr and Mo alloying element additions on the kinetics and effects of Upper Bainite formation in quench and tempered plate steels |
| title_sort | role of cr and mo alloying element additions on the kinetics and effects of upper bainite formation in quench and tempered plate steels |
| topic | Isothermal transformation Bainite Bainite Martensite structures Toughness Instrumented impact testing Dilatometry Isothermal transformation UCTD |
| url | http://hdl.handle.net/2263/33321 |