Experimental modelling of materials properties and microstructure of new UHS steels usable for press-hardening – POSTER
Press hardening is a highly dynamic process which involves rapid temperature changes. These process aspects play a major role in microstructural evolution and mechanical properties. In order to develop any thermomechanical processing sequence, including press hardening, one needs materials models of the best possible accuracy, if relevant results are to be obtained from FEM methods employed for designing metalworking processes. Therefore, relevant data on materials behaviour under real-world process conditions must be obtained experimentally. In one of such experiments, as described here, DOCOL 1800 Bor and DOCOL 2000 Bor low-alloy steels were subjected to thermal exposure identical to the heating sequence for press hardening, including the removal from the furnace and transfer to the tool. Heat treatment sequences were proposed which correspond to the thermal profiles in the actual process. The results were input into FE simulations of press hardening. In the low-alloy steels, the selected heat treatment sequence led to strengths of more than 2000 MPa and elongation levels of approx. 9%.