FEM Research And Application On Hot Rolling Of 3104 Aluminum Alloy

The microstructure and properties of hot rolled aluminum products are strongly infuenced by the processing conditions. Designing a rolling sequence is currently a trial and error process often requiring a large number of production trials to produce parts to the required specifications. This trial and error approach based on practical experience not only consumes a lot of time and money, but also can not get comprehensive rules of changes in the technical process, which delays the new materials and new product development and application.With the rapid development of computer science and physical laws in materials processing engineering, numerical simulation technology such as FEM has gained widespread application in materials science and engineering, and is profoundly changing the traditional product design and manufacturing.Various phenomena such as heat transfer, deformation and microstructural evolution occur during hot rolling, and there exists complex interplay between them. In this paper, on the basis of the experimental results and the theory of finite deformationa, a comprehensive mathematical model has been developed to predict through-thickness thermal and deformation history of 3104 aluminum sheet undergoing single-pass hot rolling using the commercial finite element package, MSC.Marc. At the same time, the influences of rolling process parameters on temperature and deformation in hot rolled Specimen is also analysed. A microstructure model, that is a "user-defined" subroutine, was employed to quantifying the microstructure (fraction recrystallised) changes that occur between the roll bite and quench. The results play a vital role in the optimization of rolling process, the prediction of product quality and the actual production guidance. The main works are briefly stated as following:1) Gleeble-1500 tester system was used to study the plastic deformation behaviors of the 3104 aluminum alloy at different temperature and deformation. Basis on experiment results, the flow stress model of 3104 aluminum alloy and its material constants are confirmed by means of mathematical statistics. The result provides the foundation of theory for the analysis of temperature, deformation and microstructural evolution in hot rolling.2) Experimental investigations of 3104 aluminum alloy were carried out on laboratory. The rolling force, temperature variation are recorded during hot rolling under different rolling schedules. A large number of dada are obtained and it provides experimental proof for the set of some complex parameters in numerical simulation calculation.3) The thermal and deformation model was developed using MSC.Marc software which couples the thermal and deformation phenomena that occur during strip rolling. The change regularity of temperature and the distribution of deformation field were analyzed during hot rolling. The effect of process parameters on change in temperature and distribution of deformation field were also studied.4) The double-stage hot deformation experiment research has been done on static recrystallization of 3104 aluminum alloy. The rules of microstructure evolution under hot process was developed and combined with the thermal-mechanical coupling finite element model. Thus, the microstructure evolution during hot rolling of 3104 aluminum alloy can be numerically simulated, and the amount of recrystallization through the thickness of the sheet can be predicted.5) Many key technologies of finite element implementation of multi-pass rolling were researched. The approach of element re-mesh solved the problem to cure serious distortion of mesh most effectively, improved the calculation accuracy and efficiency; The data transfer between different passes analyses, mainly including the node temperature, the accumulated plastic strain and user defined variables, were completed by secondary development technology of Marc; With the purpose of shortening the running time and increasing the efficiency, different time step methods are proposed for different loadcase to optimize the simulation process, and auto step technology takes the place of constant step technology according to the steady rolling state to change the control of time step and distribute the computative time in simulation.6) To examine the correctness and reliability of the model developed, the simulated results of hot rolling on an industrial "1+4" stand mill were validated by measurements from industrial environment. It shows that the simulation system is capable of analyzing the temperature, deformation and microstructure evolution of rolled strip during hot rolling. It can be used to design and optimize strip rolling process and improve the quality of products.