Study On Microstructure And Properties Of Mn-Ti High Strength Steel Under TMCP Process

The iron and steel industry is the backbone of the national economy industry,at present,The steel industry is in a critical period of dissolve excess capacity in our country,Many areas steel also puts forward the higher strength,better plasticity and toughness and good weldability at home and abroad.TMCP(Thermal Mechanical Control Process TMCP)as a new technology in the 21 st century,The high strength low carbon-alloy steel(HSLA)with TMCP technology not only obviously improve the comprehensive performance of steel,and widely used in iron production,but also play an important role in developing and manufacturing green steel material to reduce energy consumption,The technology is a hotspot of steel scholars from all over the world.This paper mainly studied Mn-Ti steel at room temperature tensile deformation and low temperature impact and thermal compression state with TMCP,obtained microstructure and mechanical properties under different experimental parameters,analyzed the evolution of the microstructure,and the effect of microstructure on mechanical properties,the paper provide the theoretical basis for parameters set in steel production combin with using conditions and requirements,The research content is as follow:(1)The room temperature tensile deformation experiment studied microstructure evolution and the tensile strength of Mn-Ti steel in 20?/s,2?/s,0.2?/s different cooling rate,determined Phase transition mechanism of the experimental steel under the cooling speed,Learned that the yield strength,tensile strength,yield ratio will significantly increases with the increase of cooling rate.(2)Mn-Ti HSLA steel cooled at 320,280,240,170 and 100? after TMCP technology,The effect of microstructure on impact toughness of steel was investigated,and the control mechanisms of many forms of ferrite,dislocation and M-A on impact toughness in different coiling temperature were analyzed.The results show that the microstructure of dislocation structure and the small M-A island ferrite is beneficial to increase of impact absorbed energy when coiled at 320-100 ?;The impact absorbed energy declines when plate strip ferrite and large M-A island appear,and it fall to minimum when the long plate strip ferrite forms.(3)The hot compress test in deformation rate of 1s-1 deformation temperature at 760?,810?,860?,910?,960? and deformation rate is respectively 0.1 s-1,1 s-1,5 s-1,10 s-1 under the 860? deformation temperature with Gleeble-3800.Research the effect of deformation rate and deformation temperature parameters on Phase change process and the the microstructure characteristics of Mn-Ti multiphase steel after cooling,to accurately control the deformation of organization,optimize the production process and microstructure.