Shuisheng Xie

FEM simulation of aluminum extrusion process in porthole die with pockets

In order to investigate the effects of pockets in the porthole die on the metal flow, temperature at the die bearing exit and the extrusion load were contrasted with the traditional die design without the pockets in the lower die. Two different multi-hole porthole dies with and without pockets in lower die were designed. And the extrusion process was simulated based on the commercial software DEFORM-3D. The simulation results show that the pockets could be used to effectively adjust the metal flow and especially benefit to the metal flow under the legs. In addition, the maximum temperature at the die bearing and the peak extrusion load decrease, which indicates the possibility of increasing the extrusion speed and productivity.

Effect of Extrusion Wheel Angular Velocity on Continuous Extrusion Forming Process of Copper Concave Bus Bar

The continuous extrusion forming process for producing large section copper concave bus bar under different extrusion wheel angular velocities was studied by three-dimensional finite element technology based on software DEFORM-3D. The rigid-viscoplastic constitutive equation was employed in the model. The numerical simulation results show that the deformation body flow velocity in the die orifice increases gradually with the increase of the extrusion wheel angular velocity. But slippage between the rod and extrusion wheel occurs when the extrusion wheel angular velocity is high. The effective stress near the die orifice enhances gradually with increasing extrusion wheel angular velocity. High stress is concentrated in adjacent regions of the flash gap. The effective strain gradient is greater near the abutment than that near the die orifice. The effective strain of the product increases gradually with increasing extrusion wheel angular velocity. In the deformation process, the deformation body temperature increases remarkably due to friction and deformation. So the cooling is necessary in the region of the die and tools.

Effect of rolling parameters on plate curvature during snake rolling

In order to predict the plate curvature during snake rolling, FE model was constructed based on plane strain assumption. The accuracy of the FE model was verified by the comparison between the plate curvature conducted by FE model and experiment respectively. By using FE model, the effect of offset distance, speed ratio, reduction, roll radius and initial plate thickness on the plate curvature during snake rolling was investigated. The experimental results show that, a proper offsetting distance can efficiently decrease plate curvature, however an excessive offsetting distance will increase plate curvature. A larger speed ratio, reduction will cause a large plate curvature, however a larger roll radius has effect to reduce plate curvature. Plate which undergoes a larger reduction and plate with a larger initial thickness always need a larger offset distance to keep the plate the minimum plate curvature, but for a larger roll radius a smaller offset distance is needed.

NUMERICAL SIMULATION MICROSTRUCTURE MORPHOLOGY EVOLUTION AND SOLUTE MICROSEGREGATION OF Al-Si-Cu TERNARY ALLOYS DURING SOLIDIFICATION PROCESS

1. State Key Laboratory for Fabrication & Processing of Non-ferrous Metals, General Research Institute for Non-ferrous Metals, No.2 Xinjiekou Wai Street, Beijing, 100088 P.R.China, Email:Xiess@grinm.com 2. School of Material Science and Engineering, Shenyang Univerisity of Technology, No.111, Shenliaoxi Road, Shenyang Liaoning, 110870, P.R.China, lq5393@sina.com 3. Henan Polytechnic University, Jiaozuo, Henan, P.R.China, 454000, Email:liqiang@hpu.edu.cn

Study on Semi-Solid Magnesium Alloys Slurry Preparation and Continuous Roll-Casting Process

Magnesium and its alloys, as the lightest functional and structural materials, have great increasingly application in the automobile, electronic and aeronautical industries due to their low density, high specific stiffness and strength, good heat conductivity, high electromagnetic interference shielding and damping capabilities, etc. However, at present the major problem to the application of magnesium alloys is still lack of suitable forming process. As a new type of metal forming method, Semi-solid metal (SSM) processing technology has attracted close attention all over the world, since M.C Flemings in MIT firstly introduced this concept in 1970s (Spencer et al., 1972), (Flemings, 1991). Compared with the conventional processes, SSM process has many advantages: higher viscosity than fully liquid, leading to laminar flow and even filling of a die; low solidification shrinkage, leading to more precise dimension product; lower casting temperature and less latent heat resulting in less thermal shock to the die. Compared with solid forming processed, SSM process needs lower loads and can fill more complicated shapes and thinner sections (Xie, 2002). The mechanical properties of SSM product are close to the forged product. So, it is significant to combine the semi-solid process techniques with continuous roll-casting techniques to produce the high quality magnesium alloy strip with non-dendritic structure. However, the key of SSM process is to prepare non-dendritic structure semi-solid magnesium slurry with rosette or globular microstructure or billets with non-dendritic structure. Usually, the nondendritic structure can be obtained by continuous stirring or controlling nucleation and growth processes during the early stages of solidification. In recent years, many new method of the semi-solid slurry preparation have been developed. These include UBE’s new rheocasting (NRC) process (Hall et al., 2000) and the Cooling Slope method (Haga & Suzuki, 2000; Haga et al, 2004; He et al, 2009); the SLC (subliquids casting) process (Jorstad et al, 2002); the “Continuous Rheoconversion Process” (CRP) (WPI, 2002), the SIMA (Strain-Induced Melt Activation) Process, the SEED (Swirled Enthalpy Equilibration Device) Process; the SCR (Shear-Cooling Roll) process and etc. In essence, all of the above-mentioned processes utilize the same fundamental concept: nucleation and dispersion of the nuclei to achieve the semi-solid structure as the alloy melt is cooled below the liquidus temperature.

Numerical Simulation and Die Optimal Design of a Large Diameter Thin-Walled Aluminum Profile Extrusion

Extrusion process of a large diameter thin-walled aluminum profile was simulated by FEM based on Deform-3D software. The results show that the material flow velocity in the bearing exit of the original designed die is non-uniform. Three times modifications were performed and simulated. The optimal design with more uniform flow velocity in the bearing exit was obtained.

Numerical Simulation of Horizontal Continuous Casting Process of C194 Copper Alloy

Horizontal Continuous Casting (H.C.C) is an important method to cast C194 copper ingot. In this paper, numerical simulation is adopted to investigate the casting process in order to optimize the H.C.C technical parameters, such as the casting temperature, casting speed and cooling intensity. According to the numerical results, the reasonable parameters are that the casting temperature is between 1383K∼1463K, the casting speed is between 7.2m/h∼10.8m/h and the speed of cooling water is between 3.6m/s∼4.6m/s. The results of numerical simulation provide the significant reference to the subsequent experiments.