Research And Devlopment Of Microalloying Hot-rolled Dual Phase Steel

With a number of unique mechanical properties such as low yielding point ,high preliminary work hardening rate good ductility,dual phase steel has been largely used in the automobile industries as a new kind of drawing steel.The application of dual phase steel sheet as structure parts in automobiles(especially incars) can reduce the weight by about 20%.It's of practical signicance to study and develop hot-rolld dual phase steel of low cost for the worldwide aims of resources saving,reduction of energy comsuption and sustainable development.In the paper,microalloying (B) hot-rolled dual phase steel was studied systemically on the basis of Si-Mn-Cr alloy.Typical dual microstructure of ferrile and martensit was observed and dual phase steel proformances was obtained by CCT diagram,micrographs and mechanism tests.Meanwhile,tensile strength (at,) of the steel was about 524-635 Mpa,total elongation (8s) was 28.0~35.0%.Both strength and toughness was enhanced.All these results proved that it was viable to use rare B to replace Mo in the tradional dual phase steel,moreover,there is a great range of reduction of cost.Chemical compositions,smelting and rolling process for rare B alloy hot-rolled dual phase steel have been oplimized in this paper. Small production has proved that this kind of steel has higher adaption to present manufacturing facility without much contracnts on the senelting and rolling process,and that it is likely to be put to wide application for its good workability to real mass production,alable mechanical performances and microstructure.