The FEM Analysis On Sectional Stress Of Round Steel In Large Section Size

This paper is based on the practice condition of the Shijiazhuang Steel Limited Company. It is adopted the method of computer simulation, tries to do some research on metal flow of round rolling steel, and then gets to know the influence of kinds of technical parameters towards inner quality of steel.This project is divided into two parts: one is theory research, the other is practical implement. The key point of the former part is inner crack of round steel during the last rolling pass. Through the simulation of the deformation stress in the process of metal deforming, we can learn the rule of the influence of kinds of technical parameters on quality of workpiece, also some methods which people can choose to use when they want to avoid inner crack of the round steel are puts forward. Metal flow is improved after changing technical parameters which is very practical to avoid inner crack.FEM software of DEFORM is adopted so that results are accurate according to the feature of deformation stress. The rule of the stress and strain distribution of the workpiece center part in X\Y\Z different direction are carefully analyzed, The influence of different technical parameters on sectional stress distribution is researched.The main contents are as follows: research on theory of the inner crack, simulation of deformation which is based on FEM software of DEFORM, and analysis of metal flow rule of the finished product when it is in the last and the last 2nd rolling pass to get distribution of residual stress. The influence of different technical parameters, such as aspect ratio and friction coefficient and roller diameter towards deformation and flow and stress distribution under the same condition of deformation degree are researched. The variation due to the non-metal inclusion is discussed. The method which can be used for preventing the inner crack from happening is put forward according to the influence of different technical parameters on sectional stress distribution after simulating rolling process of represent steel.The conclusions are as follows: The inner crack is caused by three-dimensional stress of the center of the workpiece in the zone of rolling deformation. Inner crack can be improved through the optimization of rolling pass, which is augmenting the aspect ratio of 2nd rolling pass in the inverse order. Tensile stress in the center of workpiece can be reduced through increasing the friction coefficient by raising the degree of roughness of the roller when it is reconditioned. Tensile stress in the center of workpiece can be reduced by choosing the smaller diameter roller after reconditioning if the steel is hard to prevent the happening of the inner crack. Non-metal inclusion can raise severe stress concentration which is speeding the crack polymerization and fracture. It is very practical to control the interfusion of non-metal inclusion so that inner crack can be easily reduced or avoided.The phenomenon of inner crack is greatly increased by changing the technical parameters according to the results of the simulation and analysis, inner quality is also be improved, all these are realized satisfactorily.