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Hot dip coating of high strength low carbon steels. / Geraint Wyn Lodwig
Swansea University Author: Geraint Wyn Lodwig
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Abstract
In response to increasing demand for high strength automotive steels, the development of galvanised dual phase steels has become more significant in recent years. At present, a requirement for galvanised high strength steels with tensile strengths in excess of 600 MPa exists within the automotive in...
| Published: |
2004
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| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | EngD |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa42742 |
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| Abstract: |
In response to increasing demand for high strength automotive steels, the development of galvanised dual phase steels has become more significant in recent years. At present, a requirement for galvanised high strength steels with tensile strengths in excess of 600 MPa exists within the automotive industry. The present programme focuses on seven C-Mn based steels, each steel varying in key additions such as silicon, chromium, vanadium, molybdenum and niobium. A composition range wt% of C (0.07-0.2), Mn (1.3-1.5), Si (0.05-1.3), Cr (0.05-0.45), V (up to 0.01), Mo (up to 0.01) and Nb (0.001-0.01) was studied. In order to attain these wide-ranging steel chemistries, both commercially produced and laboratory cast steels were used for this project. All steels had the required chemistry for dual phase steel production, but only if a suitable annealing cycle was used. As a result, all steels were subjected to a range of annealing cycles on a laboratory-annealing simulator, based on current continuous annealing/galvanising line schedules utilised by the Corus Group. Steels identified as dual phase steels from annealing experiments by microstructural and mechanical property analysis were subjected to laboratory galvanising. The zinc coating applied to these steels has been studied to evaluate the quality of the galvanised steel. This investigation, which has utilised a galvanising simulator, has demonstrated that during standard galvanising practices, problems known as dewetting affected the coating quality. Unfortunately, this issue was most prevalent with the steels displaying the most suitable metallurgical properties. Nevertheless, the wetting performance could be vastly improved by varying processing conditions such as annealing furnace dew point and strip entry temperature. |
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| Keywords: |
Materials science. |
| College: |
Faculty of Science and Engineering |