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Hot stamping has become an established technology for the production of high strength steel parts in the automotive industry. The sheets are heated up to temperatures over austenitization temperature and held in order to obtain a fully austenised microstructure, formed and subsequently quenched. A locally optimized time-temperature-profile during heating provides the possibility to produce tailored parts, with locally varying microstructure and thus locally adapted mechanical properties. In order to determine an appropriate partial heating strategy, the heating as well as the cooling process has to be analyzed. In this paper a numerical model of a partial heating process is investigated in LS-DYNA comprising the heating process as well as the subsequent cooling phase. In order to describe the heating process, a new material model in LS-DYNA is used, which is suited for modeling arbitrary phase transformation processes of multiple phases with help of different transformation equations. The parameters of the numerical model are determined by means of experimental tests. The numerical findings are validated by comparison with experimental masking test.
Keywords: Hot Stamping, Partial Heating, FEM, Material Characterization, Austenitization© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.