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Influence of process steps on inclusion characteristics
2003 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

In the present study, the influences of different process parameters on steel cleanness were investigated during ladle treatment of tool steel. The amount and size distribution, types and the compositions of the non-metallic inclusions during different steps of the ladle treatment were analyzed based on operational trials carried out at the steel melting shop in Hagfors. The effects of aluminum addition, alloying, vacuum treatment, the top slag composition and cleanness stirring (an operation carried out immediately after vacuum treatment), on inclusion evolution have been investigated in order to establish a relationship for the inclusion content versus process steps. The results obtained can be summarized as follows: • The inclusion contents were found to increase at the time of aluminum addition, and the types present varied along the process. • The aluminum addition to the molten steel was also found to affect the compositions of the inclusions. • Microscopic analysis of steel samples taken before vacuum degassing and after vacuum indicate that inclusion number of the size categories DT and DM decrease continuously during degassing. • Analysis of the samples taken after flotation period (AF) indicates that cleanliness stirring operation does not significantly reduce the number of the size categories DT, DM, DH and DP types and in some cases the number of the size categories DH and DP increase. • Cleanliness stirring operation was found to decrease slightly the total oxygen content (in the range of 2 ppm-6 ppm).

Place, publisher, year, edition, pages
Keyword [en]
Technology, icke metalliska inneslutningar, syreaktivitet, skänkbehandling
Keyword [sv]
URN: urn:nbn:se:ltu:diva-48797ISRN: LTU-EX--03/011--SELocal ID: 63866f25-3722-46ef-a388-afc88bd438ceOAI: diva2:1022141
Subject / course
Student thesis, at least 30 credits
Educational program
Materials Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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