STP1195

    Improved Properties of Bearing Steels by Advanced Metallurgical Processing

    Published: Jan 1993


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    Abstract

    The completion of the EAF-Ladle Degassing (LD)-Ingot Casting (IC) route at TEW, Witten works, by a Ladle Furnace (LF) together with the aluminum predeoxidation instead of the formerly vacuum carbon deoxidation (VCD) results in further improved oxide cleanness values of through-hardening bearing steels expressed by decreased macro-inclusions and oxygen contents. In the BOF-RH-degassing-IC and CC route at Thyssen Stahl, Duisburg works, the replacement of RH-degassing by the newly installed (LD) also improves the steel cleanness. Contrary to continuous casting (CC), stream shrouding in uphill IC has only a marginal effect on steel cleanness. The use of high alumina trumpet and runner bricks in uphill IC instead of fire-clay materials also does not improve the cleanness of through-hardening bearing steels. The investigation of carbon segregation in as cast ingots and continuous casting of different shapes and sizes quantifies significant differences of segregation pattern and degree. However, after an appropriate high-temperature annealing before rolling or forging, the customer's specification of carbide size and distribution is well achieved. From the comparison of the reported results with regard to cleanness and segregation, it can be concluded that continuous casting should allow the same application as ingot casting.

    Keywords:

    bearing steel, aluminum predeoxidation, vacuum carbon deoxidation (VCD), oxide and sulfide cleanness, stream shrouding in uphill ingot casting (IC), high alumina trumpet and runner bricks, continuous casting (CC), segregation, carbide distribution


    Author Information:

    Baum, R
    Director, manager, and director, Thyssen Stahl AG, Witten,

    Böhnke, K
    Director, manager, and director, Thyssen Stahl AG, Witten,

    Otto, J
    Director, manager, and director, Thyssen Stahl AG, Witten,

    Pflipsen, HD
    Director, Thyssen Stahl AG, Duisburg,


    Paper ID: STP24839S

    Committee/Subcommittee: A01.28

    DOI: 10.1520/STP24839S


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