Font Size: a A A

Numerical Simulation Of Forging Process And Microstructure Prediction For Knuckle Arm With 42CrMo Steel

Posted on:2017-05-16Degree:MasterType:Thesis
Country:ChinaCandidate:W LuanFull Text:PDF
GTID:2271330503982423Subject:Mechanical engineering
Abstract/Summary:PDF Full Text Request
As a typical low carbon steel of 42 Cr Mo which has high strength, toughness and wear resistance, are widely used in automotive crankshaft, link rod, engine shaft and other parts requiring high mechanical properties. Automotive steering knuckle arms is an important load-bearing part of steering system and its forming process and quality of product is direct impact on the productivity of company and the performance of the car. Therefore, the constitutive equation and microstructure evolution models can be established through experiments and the finite element software Deform-3D can be used to simulate the hot forming process of automotive steering knuckle arms of 42 Cr Mo steel and predict its microstructure distribution based on the models. Then optimizes and improves the original process of blank.Hot compression tests were conducted on 42 Cr Mo steel by Gleeble-3800 thermal simulated machine.Stress-strain curves of 42 Cr Mo steel under different deformation conditions were obtained. The influence rule of deformation temperature and stain rate on its flow stress were analyzed. Through the fitting of experimental data, thermal deformation performance parameters of 42 Cr Mo steel as a function of Z parameter were established. And the constitutive model suitable for hot deformation process of 42 Cr Mo steel was established further based on the hyperbolic sine equations of Arrhenius-type. And finally verify the accuracy of the constitutive equation by comparing the final stress calculated and experimental values.The influence rule of different deformation parameter on recrystallized grain size and recrystallization volume fraction of 42 Cr Mo steel during hot deformation process was obtained through the metallographic sample preparation for the compression specimens and the statistic analysis of data. The dynamic recrystallization model of 42 Cr Mo steel during hot forging process were established based on statistic data. And finally verify the accuracy of the model of dynamic recrystallization by comparing the final recrystallized grain size and volume fraction calculated and experimental values.Through the stress-strain curve, the processing maps of 42 Cr Mo steel at several strains are established based on DMM and analysis the influence law of unstable region with strain. And ultimately determine the optimum range of hot forging process of 42 Cr Mo steel by the processing maps.The established constitutive model and dynamic recrystallization model were imported into Deform-3D software to simulate the forming process of automotive steering knuckle arms of 42 Cr Mo steel. According to the simulation results, the temperature of the forging and the change rule of stress, strain and the reason of defect were analyzed. And the mean grain size, the recrystallization volume fraction and some other microstructure evolution parameter were predicted.Instead of using the cross-wedge rolling to make blank is the new development direction. And the designed cross-wedge rolling dies with selected paremeters were imported into Deform-3D software to simulate the rolling process.According to the simulation results, the temperature of the forging and the change rule of stress, strain and the reason of defect were analyzed. And the mean grain size, the recrystallization volume fraction and some other microstructure evolution parameter were predicted.
Keywords/Search Tags:42Cr Mo steel, automotive steering knuckle arms, constitutive equation, microstructure evolution model, cross-wedge rolling, finite element simulation
PDF Full Text Request
Related items