Effect Of Alloying And Heat Treatment On Microstructure And Mechanical Properties Of GX160CrMoV12 Steel

GX160CrMoV12 steel has the characteristics of high hardness and high wear resistance,and is widely used in the field of mold manufacturing and machinery manufacturing.However,coarse mesh eutectic carbides are distributed on the grain boundaries of GX160CrMoV12 steel,which significantly reduces the strength and toughness of the steel.Therefore,there is a need to improve the morphology and distribution of eutectic carbides on its grain boundaries.Enhancing the toughness of GX160CrMoV12 steel on the basis of ensuring its hardness is the key to applying GX160CrMoV12 steel to the impact crusher plate hammer.This article takes GX160CrMoV12 steel as the research object,through adding Ti,Ni,Y and other micro-alloying components and heat treatment process optimization,combined with metallographic observation,SEM and EDS analysis,XRD analysis,hardness and impact toughness testing methods to study microalloys The effect of chemical and heat treatment on the structure and mechanical properties of GX160CrMoV12-Ti-Ni-Y steel,GX160CrMoV12-Ti-Ni-Y steel was prepared with optimized alloy composition and heat treatment process.The following main conclusions are drawn:(1)Adding 0.5%Ti can significantly refine the eutectic carbide of GX160CrMoV12 steel.The amount of Ni added increased from 0.5%to 1.5%,the as-cast microstructure was equiaxed,and the secondary dendrite arm was coarsened.The amount of Y added increased from 0.1%to 0.3%,the grain size of the as-cast equiaxed grain structure was reduced,the secondary dendrite arms were refined,and the eutectic carbide morphology changed from coarse bulk to fine strips and isolated islands,The distribution changes from continuous network to discontinuous network.The grain size of GX160CrMoV12-0.5Ti-1.5Ni-0.3Y steel is fine,the size of eutectic carbide is the smallest and the distribution of broken network,the highest hardness is 44HRC,which is the most optimized composition of as-cast alloy.(2)The spheroidizing effect of GX160CrMoV12-0.5Ti-1.5Ni-0.3Y steel after annealing at an isothermal temperature of 740℃is the best,and the spherical carbides are dispersed in the crystal;Due to the low isothermal temperature of 720℃,the diffusion is limited,and the microstructure is short flake pearlite+eutectic carbide;due to the high isothermal temperature of 760℃,the eutectoid transformation of supercooled small pearlite does not completely.(3)The structure of GX160CrMoV12-0.5Ti-1.5Ni-0.3Y steel after quenching at960℃is hidden needle martensite+residual austenite+carbide.As the quenching temperature increases,the eutectic carbide gradually dissolves,the size of martensite becomes larger,the content of residual austenite increases,and the hardness increases first and then decreases.The optimal quenching temperature is 1040℃.At this time,the general network carbide has a general melting phenomenon,the distribution is more dispersed,the matrix is fine needle martensite,the hardness is 61.6HRC,which is 8%higher than the hardness of GX160CrMoV12 steel.(4)The structure of GX160CrMoV12-0.5Ti-1.5Ni-0.3Y steel after tempering at100℃,200℃and 300℃is tempered martensite+eutectic carbide.As the tempering temperature increases,the hardness decreases and the impact toughness increases.The optimal tempering temperature is 200℃,the hardness is 61.4HRC,and the impact toughness is 11.3 J/cm~2.Compared with GX160CrMoV12 steel,the impact toughness of GX160CrMoV12-0.5Ti-1.5Ni-0.3Y steel is increased by 69%,and its hardness is increased by 9%.