A unified mechanism for the formation of oscillation marks

Pavel E. Ramirez Lopez, Kenneth C. Mills, Peter D. Lee, Begona Santillana

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Oscillation marks (OMs) are regular, transverse indentations formed on the surface of continuously cast (CC) steel products. OMs are widely considered defects because these are associated with segregation and transverse cracking. A variety of mechanisms for their formation has been proposed (e.g., overflow, folding, and meniscus freezing), whereas different mark types have also been described (e.g., folded, hooks, and depressions). The current work uses numerical modeling to formulate a unified theory for the onset of OMs. The initial formation mechanism is demonstrated to be caused by fluctuations in the metal and slag flow near the meniscus, which in turn causes thermal fluctuations and successive thickening and thinning of the shell, matching the thermal fluctuations observed experimentally in a mold simulator. This multiphysics modeling of the transient shell growth and explicit prediction of OMs morphology was possible for the first time through a model for heat transfer, fluid flow, and solidification coupled with mold oscillation, including the slag phase. Strategies for reducing OMs in the industrial practice fit with the proposed mechanism. Furthermore, the model provides quantitative results regarding the influence of slag infiltration on shell solidification and OM morphology. Control of the precise moment when infiltration occurs during the cycle could lead to enhanced mold powder consumption and decreased OM depth, thereby reducing the probability for transverse cracking and related casting problems. © The Minerals, Metals & Materials Society and ASM International 2011.
    Original languageEnglish
    Pages (from-to)109-122
    Number of pages13
    JournalMetallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science
    Volume43
    Issue number1
    DOIs
    Publication statusPublished - Feb 2012

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