Study On Microstructure And Properties Of Hot Rolled Medium Manganese Steel Under Alloying Element Parting

As a new generation of advanced automobile steel,medium manganese steel has not only high strength but also high plasticity.The key to its excellent performance lies in its large amount of retained austenite and ultrafine grain structure.The most effective and reasonable way to obtain a large amount of retained austenite is to use the alloy elements added to the steel to carry out the distribution.During the distribution process,the alloy elements diffuse from martensite to austenite phase,so that a large number of alloy elements are enriched in the austenite phase,and the stability of austenite is increased,so that the austenite will not undergo martensitic transformation in the subsequent cooling process,which can be in the room Stable at temperature.Therefore,the study takes 0.3c-6mn steel as the research object,using isothermal compression test and hot rolling +I&Q&P process,to study the effect of recrystallization refining grain behavior and alloy element distribution behavior on the microstructure and properties of medium manganese steel.The results are as follows:The behavior of recrystallization and grain refinement was studied by isothermal compression test.The constitutive equation,hot working diagram and dynamic recrystallization behavior of the material were obtained from the rheological curve obtained by the test.The recrystallized fine grain structure was prepared according to the best hot working window obtained.The reasonable selection of heat treatment parameters can accelerate the diffusion rate of C and Mn in the two-phase region,and promote the effect of alloy element distribution of C and Mn in the two-phase region.After 60 minutes at 625 ℃,the size of retained austenite is 0.58 μ m,and the grade is submicron.The maximum volume fraction of retained austenite is 21.10%,and the content of C in retained austenite is 1.3%.The tensile strength at room temperature is 1120 MPa,the elongation reaches29.10%,and the strong plastic product reaches 32.54 GPa%.Through the analysis of tensile fracture,it is found that the main fracture structure is dimple structure.Figure57;Table13;Reference 97...