Influence of ferromanganese additions on microalloyed engineering steel
2003 (English)In: Ironmaking & steelmaking, ISSN 0301-9233, Vol. 30, no 1, 73-80 p.Article in journal (Refereed) Published
Plant trials with the addition of four different low Carbon and medium carbon ferromanganese alloys to microalloyed engineering steels have been carried out at Ovako Steel, Hofors, Sweden. The process route for this type of steel at Ovako is electric arc furnace (EAF), ladle arc furnace (LAF), ASEA-SKF vacuum degasser, LAF and finally uphill teeming. For each ferromanganese alloy type, five experiments were accomplished by adding alloy at the ladle furnace station, i.e. 20 charges in total. During the experiments, liquid steel rapid solidification samples were taken to study the behaviour of inclusion formation and removal during ladle treatment. Also, samples for LSHR testing (liquid sampling hot rolling) were acquired for one heat of each of the ferromanganese containing alloys. Microinclusion assessments were carried out according to the method described in Swedish standard SS 111116. Macroinclusion assessments were carried out using immersed ultrasonic testing. Element analysis and mappings were done using a scanning electron microscope to establish the effect of ferromanganese addition on the composition of inclusions present in the steel. In samples taken 3 min after the ferromanganese addition to the LAF, about 30% of the analysed inclusions contain Al2O3, MnO and MnS. The Al2O3 content is concluded to originate from the deoxidation practice, while MnO and MnS contents are likely to originate from the addition of ferromanganese. The results also show that the addition of ferromanganese alloys leads to an increased amount of macroinclusions in the LAF up to 9 min after alloy addition. Steel samples taken after degassing but just before casting indicate that all the tested ferromanganese alloys give the same result with respect to the studied microinclusion characteristics at the end of ladle treatment. Last, the inclusion composition in the final steel samples is unrelated to the type of ferromanganese alloy used. In this case, the main compositions are Al2O3-MgO and MnS.
Place, publisher, year, edition, pages
2003. Vol. 30, no 1, 73-80 p.
IdentifiersURN: urn:nbn:se:kth:diva-22309DOI: 10.1179/030192303225009461ISI: 000181490000010OAI: oai:DiVA.org:kth-22309DiVA: diva2:341007
QC 201005252010-08-102010-08-10Bibliographically approved