The Study of Controlled Cooling Technology and Warping of X65 Heavy Pipeline Plate

A thermo-mechanical coupled finite element model is established,which combines the modified Avrami transformation dynamics model,the linear mixture thermal expansion model,and the Leblond transformation induced plasticity (TRIP) model.The model considers latent heat,transformation dilatation,TRIP effect,as well as thermal expansion and elasto plastic deformation.The influence of three different controlled cooling modes on temperature field and stress,strain field of X65 heavy pipeline plate is simulated and the warping of plate is analyzed.The result shows that the main reason of warping is the temperature difference between the top and bottom surfaces from unsymmetric cooling,which causes the unsymmetric distribution of stress and strain field.Alternate cooling,in which laminar cooling and air cooling appear alternately,decreases the temperature difference and reduces the magnitude of warping strongly.To avoid warping and to realize the uniformity of properties,it is more effective to maintain the cooling homogeneity between the top and bottom surface of plate during controlled cooling,and to use alternate cooling.