Study On Hot Deformation Behavior And Microstructure Refinement Of EH40 Extra Thick Ship Plate Steel

With the rise of China's shipbuilding industry,higher requirements are put forward for the strength,toughness and weldability of ship plate steel.The thickness section effect(deformation and temperature)of extra thick plate is a common problem in production,which directly affects the homogeneity of structure and property of steel plate.At present,there is a lack of effective theory to guide the production practice of extra heavy plate,and most of them organize production by trial and error method.In this paper,EH40 extra thick ship plate steel is taken as the research object,and the characteristics of its high temperature deformation are studied.Based on the results of single pass hot compression experiment,the Arrhenius constitutive equation,peak strain model and dynamic recrystallization dynamic model are established,and the processing map of EH40 ship plate steel is constructed according to the dynamic material model.The results of double pass compression test show that: according to the static softening rate under different deformation conditions,during the rolling process of EH40 ship plate steel,the rolling temperature is more than 1000?,the pass interval time is more than 5s,which can improve the static recrystallization volume fraction and refine the grains after rolling.and establish the dynamic model of static recrystallization.The rolling process is simulated by DEFORM.The results show that the pre rolling water-cooling experiment and the inter pass water-cooling experiment are beneficial to the improvement of the core deformation of the rolled piece,and the rolling experiment in the laboratory verifies that the pre rolling and inter pass water-cooling can reduce the influence of the structure cross-section effect in the thickness direction;the increase of the reduction can increase the stress variable of the core structure,while the change of the rolling speed has little effect on the variable,and through the hot rolling experiment In compression test,it is found that the microstructure is smaller with the increase of reduction.