EBSD Study of Substructure and Texture Formation in Dual-Phase Steel Sheets for Semi-Finished Products

摘要

Using SEM/EBSD the substructure and texture evolution in dual phase steels in the first steps of the process chain, i.e. hot rolling, cold rolling, and following annealing were characterized. In order to obtain dual phase steels with high ductility and high tensile strength an industrial process was reproduced by cold rolling of industrially hot rolled steel sheets of a thickness of 3.75mm with ferrite and pearlite morphology down to a thickness of 1.75mm and finally annealing at different temperatures. Such technique allows a compilation of ferrite and martensite morphology typical for dual phase steels. Due to the competition between recovery, recrystallization and phase transformation during annealing a variety of ferrite martensite morphologies was produced by promoting one of the mechanisms through the variation of technological parameters such as heating rate, intercritical annealing temperature, annealing time, cooling rate and the final annealing temperature. Annealing induced changes of the mechanical properties were determined by hardness measurements and are discussed on the basis of the results of the substructure investigations.