Bainite in Multiphase Steels: microstructure – property relationship

  microstructure – property relationship IEHK

Due to the combined effects of the different microstructure components with varying mechanical/physical properties, multi-phase steels are highly interested by steels and automotive industry. In such complex phase steels, besides ferrite and martensite which are well understood phase and quantitatively modelled in terms of properties, bainitic phase is another significant role. The partially bainitic microstructure reduce the property gradient between hard martensite phase and soft Ferrite phase, which improve the strength and formability of these grades.

In the present context, the term „bainite“ describes a microstructural constituent consisting of finely-dispersed lath-shaped ferrite, carbides and retained lath-like or spherical austenite grains. Thus, the phase intrinsically has a complex substructure and morphology. In order to investigate the influence of microstructure on mechanical property of bainite added multiphase steel (CP800), various characterization techniques (for microstructure and micromechanics) have been performed and overlapped. Furthermore, the development of a physical-based simulation approach on the microstructure scale for the microstructure – property relationship of bainite in low-alloyed multiphase steels is necessary and to implement this into an existing dual phase model.

This research is carried out under the Project No. MC in the framework of the Research Program of the Materials innovation institute M2i, the former Netherland Institute for Metals Research.