Study On The Uniformity Of Deformation In Temperature Gradient Rolling Of Thick Steel Plate

Demand for thick steel plates with high properties is growing in the ocean scope, transportfield, energy aspect as well as important equipment area.Deformation of thick steel plate along the thickness direction was non-uniform during the traditional hot rolling, with which was a small compression ratio in center. The deformation cannot penetrate from the face layer to the center made the defects unbinding. Cross shear rolling could improving the penetration of the rolling deformation, while it would result in a warped plate. Temperature gradient rolling method was a process that rapid cooling while rolling and the center of thick plate could not cool down, so that a non-uniform temperature distribution was forming that low temperature on surface and high temperature in center. With this rolling method, the harden layer on the surface could prompt the deformation penetrated form the surface to the center, which could remove the defects in the center of the thick plate to enhance uniformity of the deformation along the thickness direction.This paper studied uniformity of the deformation of thick steel plate with the temperature gradient rolling method and controlled head warping of cross shear rolling through the rolling method by means of ANSYS/LS-DYNA finite element software. Theoretical basis of numerical analysis was provided for setting up and perfecting process system of temperature gradient rolling method. The main research results were as follows:Physical experiments of isothermal rolling and temperature gradient rolling of thick plate were finished in Φ450rolling mill, Experimental results showed that:temperature gradient rollinghas greater heart compression deformation thanisothermal rolling.Regularities of temperature distribution of UFC cooling situation at different experiment conditionswere analyzed. The results indicated that thermal drop was main intensively taking place at1/5layer form surface of the plate and the average cooling rate was5～20℃/s。ANSYS finite element model of the temperature gradient rolling method was built, and the effect of different processes(Compression ratio, Initial thickness, Diameter of roller, Rolling speed, Coefficient of friction, Coefficient of heat transfer and Cooling time) on the deformation uniformity was simulated. The results showed that temperature gradient rolling could increase compression deformation in the center of the thick plate and enhance the deformation uniformity along the thickness direction at different UFC cooling conditions. Compression ratio, cooling intensity and cooling time were the key factors for affecting the deformation uniformity. Reasonable coupling technics for temperature gradient rolling were given at the same time.ANSYS finite element model of temperature gradient-cross shear rolling method was built, and primary research that controlling of head wrapping of the temperature gradient-cross shear rolling method was making. The results indicated that:the head wrapping of the cross shear rolling with velocity ratio of rolls in1.017～1.135could be controlled by the temperature gradient rolling.