Simultaneous Modification of Alumina and MgO·Al{sub 2}O{sub 3} Inclusions by Calcium Treatment During Electroslag Remelting of Stainless Tool Steel

Journal Article · Tue Feb 14 23:00:00 EST 2017 · Metallurgical and Materials Transactions B, Process Metallurgy and Materials Processing Science

DOI:https://doi.org/10.1007/S11663-016-0771-1· OSTI ID:22856104

Shi, Cheng-Bin; Yu, Wen-Tao; Wang, Hao; Li, Jing; Jiang, Min ^[1]

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1. University of Science and Technology Beijing (USTB), State Key Laboratory of Advanced Metallurgy (China)

Calcium modification of both alumina and MgO·Al{sub 2}O{sub 3} inclusions during protective gas electroslag remelting (P-ESR) of 8Cr17MoV stainless steel and its effect on nitrides and primary carbides were studied by analyzing the transient evolution of oxide and sulfide inclusions in the P-ESR process. The oxide inclusions that were not removed during P-ESR without calcium treatment were found to retain their original state until in as-cast ingot. Calcium treatment modified all MgO·Al{sub 2}O{sub 3} and alumina inclusions that had not been removed in the P-ESR process to liquid/partially liquid CaO-Al{sub 2}O{sub 3}-(MgO) with uniformly distributed elements, in addition to a small proportion of partially modified inclusions of a CaO-MgO-Al{sub 2}O{sub 3} core surrounded by a liquid CaO-Al{sub 2}O{sub 3}. The modification of low-MgO-containing MgO·Al{sub 2}O{sub 3} inclusions involves the preferential reduction of MgO from the MgO·Al{sub 2}O{sub 3} inclusion by calcium and the reaction of calcium with Al{sub 2}O{sub 3} in the inclusion. It is the incomplete/complete reduction of MgO from the spinel by calcium that contributes to the modification of spinels. Alumina inclusions were liquefied by direct reaction with calcium. Calcium treatment during P-ESR refining also provided an effective approach to prevent the formation of nitrides and primary carbides in stainless steel through modifying their preferred nucleation sites (alumina and MgO·Al{sub 2}O{sub 3} inclusions) to calcium aluminates, which made no contribution to improving the steel cleanliness.

• OSTI ID: 22856104
• Journal Information: Metallurgical and Materials Transactions B, Process Metallurgy and Materials Processing Science, Journal Name: Metallurgical and Materials Transactions B, Process Metallurgy and Materials Processing Science Journal Issue: 1 Vol. 48; ISSN 1073-5615; ISSN MTBSEO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINATES
ALUMINIUM OXIDES
CALCIUM
CALCIUM OXIDES
CARBIDES
DIRECT REACTIONS
INCLUSIONS
LIQUIDS
MAGNESIUM OXIDES
NITRIDES
NUCLEATION
SPINELS
STAINLESS STEELS
SULFIDES