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  • A multi-scale friction model for hot stamping

    6 Jun 2019

    Jenny Venema, Eisso Atzema;Tata Steel R&D, IJmuiden
    Javad Hazrati, David Matthews, Ton van den Boogaard; University of Twente, Enschede

    Finite element (FE) analysis is common in sheet metal forming industries to perform feasibility analyses and to optimize processes. In hot stamping, sheet metal is formed at high temperatures (600-800 ºC) which leads to complex tribological phenomena at the tool-sheet contact characterized by severe wear and high friction. Thus, to improve the validity and accuracy of these FE analyses, it is necessary to accurately describe friction in FE analyses of hot stamping processes. So far, in the FE analyses friction is oversimplified using e.g. a constant Coulomb’s friction. However, it has been shown that friction is a local phenomenon that depends on the micro-texture of tool and sheet at the contact and varies with contact pressure, strain in the bulk of the sheet and contact temperature. In this study, the influence of pressure and temperature on the friction and wear behaviour of press hardening steels (with an AlSi based coating) is investigated. A multi-scale friction model is developed that accounts for the local contact pressure, temperature and strain in the bulk. Furthermore, the effects of tool and sheet metal surface topography are taken into account. The results show that the model can predict the friction in strip-draw experiments fairly well, when incorporating the tool surface evolution due to wear.

    Paper presented at the CHS2 - International conference on Hot Sheet Metal Forming of High Performance Steel, Luleae, Sweden 2-5 June 2019 

    DOI not available