In order to optimize the heat treatment process,control the ratio of quenching microstructure and develop ultra-high strength steel with better strength and plasticity,the effect of quenching temperature on the microstructure and properties of 40CrNiMo steel was studied by means of optical microscope,scanning electron microscope and electron backscatter diffraction combined with microhardness test and tensile test.It is found that when the quenching temperature is lower than Ac1,the micro-structure is composed of granular pearlite and lamellar pearlite.During quenching in the two-phase region,as the temperature in-creases,the cementite gradually dissolves,the quenched martensite gradually increases,and the proportion of irregular undis-solved ferrite continues to decrease.When quenched at 790 ℃,the microstructure is complete martensite in lath shape.With further increase of the quenching temperature,the original grain size increases,martensite lath coarsening.With the increase of quenching temperature,the proportion of martensite in the microstructure increases,resulting in a significant increase in the hardness and strength of the experimental steel.Compared with the complete martensite structure,retaining a certain proportion of ferrite can further improve the strength of the material,while having good work hardening properties and plasticity.The fer-rite(28％)+martensite dual-phase structure of 40CrNiMo steel is formed by reasonable regulation of microstructure.The high strength and toughness of quenched steel are realized by the mechanical incompatibility of different microstructures,which pro-vides a theoretical support for further exploring the mechanical properties of traditional structural materials.
关键词
40CrNiMo钢/淬火工艺/组织调控/力学性能/强韧化
Key words
40CrNiMo steel/quenching process/microstructure control/mechanical property/strengthening and toughening
维普
万方数据