Thermo-mechanical Coupling FEM Analysis Of Hot Rolling Deformation Of X100Pipeline Steel

Pipeline transport is an effective means to transport oil and gas of long distance, with the characteristics of high efficiency, economy, safety and no pollution. With the widespread application of X80pipeline steel, researchers focus their attention on the development of X100and above high-grade pipeline steel to reduce the cost of pipeline construction and operation further. But the development of X100pipeline steel not only requires a lot of manpower, material and financial resources; but exists some technical restrictions.With the rapid growth of computer technology and the gradual maturity of computational material science, using computer simulation to study the hot-rolled forming process of pipeline steel has become one of the most effective methods. There’re some researchers who have used computer technology to simulate the thermo-mechanical coupling fields of medium thickness sheet in hot rolling process. But most of the researchers set the roller as rigid to simplify the simulation, built the model as two-dimensional or three-dimensional of steady-state, choose indirect coupling method to deal with the coupling of temperature field and stress field, or convert the radiation boundary condition to convection boundary conditions, etc, and the methods above will bring about deviation. Thermo-mechanical simulation has been studied for X100pipeline steel in this paper. The direct coupling method is used to the three-dimensional finite element model. It is nonlinear of material’s stress-strain, geometric large deformation and contacted boundary conditions that are considered in this paper. The whole roller is set to be elastic, coupling of temperature field and stress field are set direct coupling and the boundary condition of the convective heat, the contact heat transfer and the radiative heat are set according to the actual heat transfer of the hot rolling process.The hot rolling process has been simulated with rolling temperature from1000℃to1100℃, rolling reduction from20%to40%and the rotating speed of roll from27.2rpn to37.2rpn. It is studied that the effects of rolling temperature, reduction and rotating speed of roll on rolling flatness, distributions of temperature, residual stress and strain. The law of Plastic deformation of variation, stress-strain fields, temperature and rolling force are analyzed. The effects are as follows:(1) When the roll temperature is100CTC, the reduction is40%and the rotating speed of roll is37.2rpn, the distribution of the strip is the most even.(2) When the temperature is1100℃, the reduction is20%and the rotating speed of roll is27.2rpn, the rolling flatness is the most smooth.(3) When the roll temperature is1100℃, the reduction is40%and the rotating speed of roll is37.2rpn, the residual stress distribution on the surface of the strip is the most even; When the roll temperature is1000℃, the reduction is20%and the rotating speed of roll is32.2rpn, the residual stress distribution on the side of the strip is the most even.(4) When the roll temperature is1000℃, the reduction is20%and the rotating speed of roll is27.2rpn, the rstrain distribution on the surface of the strip is the most even; When the roll temperature is1000℃, the reduction is30%and the rotating speed of roll is37.2rpn, the residual stress distribution on the side of the strip is the most even.There is no report about thermal-mechanical direct coupling with a full range of thermal boundary conditions in the field of thermal-structure coupling simulation for hot rolling process. This study provides a theoretical guidance to improve and optimize the rolling process, and provides a basis for further study of organizational evolution and performance predictionthe rolling process.