Study on the Mechanism of Improving the Formability of DP Steel LTWB at the Elevated Temperature Level

摘要

In the present work, warm tension tests for DP steel LTWB (B340/590DP) with 1.0mm/1.0mm thickness are performed on the CMT5205 universal tester, and its microstructure in the region adjacent to weld line is observed by the JSM-7001F scanning electron microscopy. Moreover, Imagetool software is applied to deal with the SEM photographs in order to study the influence of forming temperature on the martensite volume fraction, average length and thickness. By building the relationship of martensite structure volume fraction, feature size, configuration with macro-mechanical properties including stress peak, yield strength, elongation at failure and temperature, the mechanism of improving the formability of DP steel LTWB at the elevated temperature level is revealed, which is vital for optimizing the warm forming process parameters of DP steel LTWB and setting up the precise material constitutive model to enhance the FEM simulation accuracy.