Study On The Mechanism And Microstructure Evolution Of 42CrMo Conjunction Gear During Forging Process

The object studied is the steel 42CrMo for gear,which is a transmission conjunction gear in a certain automobile gearbox.42CrMo steel(approximately American grade AISI-4140)belongs to medium-carbon low-alloy steel.It has high strength,toughness,and good hardenability.It is widely used in various parts of automobile gearboxes,including automobile crankshafts,plungers,shafts and combined gears,etc.The Gleeble-1500D thermomechanical simulator is used for thermal compression under the temperature of 800?1200?and a strain rate of 0.01?10s^-1 was studied,and the strain compensated Arrhenius constitutive equation of 42CrMo gear steel was established.The correlation coefficient between experimental data and predicted data reaches 0.995.This shows that the Arrhenius constitutive equation has high accuracy in predicting 42CrMo gear steel.the Gleeble-1500D simulator used for thermal compression under theAccording to the dynamic material theory(DMM),the thermal processing maps of the real strains of 0.2,0.4,0.6,0.4 and 0.8 are obtained.Using the specimen after compression test,after a series of processes such as polishing and corrosion,the quenched microstructure of the experimental material was studied with an electron microscope(SEM).The research of processing map combined with metallographic experiment verified the rationality of thermal processing map as a guide for actual production.And the best heat treatment parameter range of the material is obtained:the temperature range is 1000C?1125?,and the strain rate range is 3.16?10s^-1.The dynamic recrystallization volume fraction model and grain size model of the material were established.The recrystallization model and constitutive equation data were imported into Deform-3D software,and the finite element numerical model was established.The forming mechanism and microstructure evolution of 42CrMo conjunction gear forging were studied and discussed.The response surface method was used to optimize the processing parameters:531.51mm/s,950?,0.12,and the average grain size was 17.88um,and the average grain size at the tooth profile was 9.80um.Figure 44;Table 16;Reference 65...