A modified two-dimensional (2-D) cellular automaton (CA) model was constructed to simulate dynamic recrystallization (DRX) process of GCr15 steel. Particle stimulated nucleation (PSN) was incorporated into the CA model to determine the influence of dispersed particles on the nucleation of DRX. In addition, the model included the effects of particles on increasing the dislocation density and pinning the grain boundaries for accurate determination of micro-structural evolution during DRX. The model was applied to simulate the DRX process of GCr15 bearing steel. DRX grain size and volume fraction were simulated using the CA model. The simulated results indicated that the simulated stable grain size of particle-containing model is closer to measured value than particle-free model. It was observed that DRX kinetics depends on both thermo-mechanical parameters and initial grain sizes. The calculated results were compared with the experimental findings in GCr15 bearing steel, the predictions show very good agreement with the experimental results.

Electrically assisted compression experiments were conducted on Ti6554 titanium alloy to investigate the electroplasticity behavior under different process parameters (current density, duty cycle) and to analyze the effect of pulsed current on flow stress and temperature. An electroplasticity constitutive model based on dislocation density theory was developed and using ABAQUS subroutine secondary development for electrically assisted compression simulation. The results show that the established electroplasticity constitutive model can better predict the true stress-strain curves under different process parameters, and the average error is controlled at 6%. The evolution law of dislocation density reveals that α, which characterizes the dislocation strength, is smaller with the increase of current density, n and K2, which characterize the dynamic recovery mechanism of the material, increase with the increase of current density, and the dislocation density ρ decreases with the increase of deformation temperature.

The excessive residual stress induced by quenching in steels will easily result in distortion and failure of parts. In order to obtain the more suitable quenchant, quenching process of Cr12MoV steel with different mediums involving water and oil are simulated, respectively. In present paper, the influence of nonlinear surface heat transfer coefficient, thermodynamic parameters and latent heat are considered comprehensively. The distribution of temperature, microstructure, hardness and residual stress after quenching for Cr12MoV steel are simulated by DEFORM finite element software. According to the results mentioned above, the variations of each field of the steel are analyzed.

Temperature evolution is one of the important parameters of mechanical properties of thin strip products. So the ability of prediction of temperature history before processing is critical to the processing scheme of controlling rolling and controlling cooling. In this paper an integrate model of finite element method is presented for the prediction of the temperature evolution in the finishing rolling during hot strips. The model takes into account the interaction between thermal behavior and mechanical behaviors. By using the second-development method based on the commercial code thermal behavior and temperature distribution of strips through seven-pass finishing rolling are described in detail. A method for computing the mean temperature at the exit of each pass is approached. Using this method the mean temperature can be attained after each pass. In one seven-pass thin strip rolling mills the temperature at the exit after each pass is measured by the pyrometer. The measured results and the simulation results are compared. The validity of the proposed analysis model is examined. The computing results are in agreement with the measured results.

The recent application of tube hydroforming in the automotive industry demands finite element analysis, since it is rapidly being used as an effective tool for the evaluation of the design of hydroforming processes. In this paper the formability of rear sub-frame in car body with tube hydroforming is studied. The comparison of various feeding and pressure on the hydroforming process is evaluated utilizing Finite Element Method to obtain detailed information on the deformation behaviors in hydroforming of rear sub-frame. It has been shown that optical leading paths such as axial feeding and internal pressure can quantify the circumferential thickness distribution in the rear sub-frame tube periphery.