Numerical Simulation And Tehcnological Optimization Of Spray Quenching Process Of Cr5 Forged Backup Roll

Numerical simulation technology is indispensably important means for thequenching process research and quenching technological design. Because of complexmulti-field coupling phenomenon and boundary conditions during the quenching processof large Cr5 forged backup roll, it has been a difficulty of heat treatment numericalsimulation field. To simulate the spray quenching process of large Cr5 forged backup rollnot only can be used to develop and improve its quenching process, which canaccomplish many aims that reduce cracks and distorts, control and guarantee quality, butalso could improve its using performance, so it has important theoretical and practicalsignificance.This paper employs experimental results of transformation plasticity parametersprediction about Cr5 steel，employs the transformance plasticity theoretical model whichbuilt according to the multiaxial stress flow rule, and considers latent heat and othervaricble physical property parameters, to beter perfect the whole mechatical model so asto be used to calculate the coupled temperature-microstructure-stress field duringquenching prccess of large Cr5 forged backup roll. This paper utilizes the finite elementsoftware HYPERMESH to generate hexahedron mesh for lage Cr5 forged backup roll,and utilizes the finite element software DEFORM to simulate its spray quenching process.After the simulation, the change rule and distribution characteristics of temperature,transient stress, and transformation characteristics of miscrostructure about feature nodeshave been given.This paper puts forward two improvement plans on the base of shortcomings suchas excessive temperature gradient on middle section of backup roll, the highertemperature of centre, and the larger quenching residual stress of original quenchingprocess, which are“fog quenching and then air spray quenching process”and“fogquenching and air spray quenching alternately”. Time parameters of fog cooling and aircooling are determined according to the numerical simulation research of quenchingprocess. Finally，the main field parameters, such as the surface and center temperature of backup roll, surface hardenability, the depth of hardened layer, and the residual stress, areanalyzed. Overall, two improved process have better reduced the quenching residualstress and regulated the temperature gradient on the section of backup roll. The researchachievement of the paper has a certain guiding significance to developing and improvingquenching process of large Cr5 forged backup roll.