Research And Application On Hot Forming Properties Of 300M High Strength Steel

As a kind of widely used low-alloy high strength steel,300 M is often used for the manufacture of various important bearing components. The main forming method for its forgings is hot forging and the forging process parameters has great impact on the microstructure and mechanical properties of 300 M steel forgings. 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 300 M steel forging and predict its microstructure distribution based on the models. This is very important to control the quality of large forgings.In this paper, hot compression tests were conducted on 300 M high strength steel by Gleeble-3800 thermal simulated machine. Stress-strain curves of 300 M high strength steel under different deformation conditions were obtained. The influence rule of deformation temperature, stain rate and interval holding time on its flow stress was analyzed. Through the fitting of experimental data, thermal deformation performance parameters of 300 M steel as a function of Z parameter were established. And the constitutive model suitable for hot deformation process of 300 M steel was established further based on the hyperbolic sine equations of Arrhenius-type.The influence rule of different deformation parameter on mean grain size,recrystallized grain size, recrystallization volume fraction of 300 M high strength 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, meta-dynamic recrystallization model and static recrystallization model of 300 M high strength steel during hot forging process were established based on statistic data.The established constitutive model and microstructure evolution models were imported into Deform-3D software to simulate the forming process of 300 M landing gear cylinder die forging. According to the simulation results, the forming conditions of the forging and the change rule of stress, strain and et al were analyzed. And the mean grain size, the recrystallized grain size, the recrystallization volume fraction and some othermicrostructure evolution parameter were predicted. Finally simulation results and experimental results under the same deformation condition were compared which verified the correctness of the simulation.