| The rapid development of shipbuilding industry,puts forward higher requirements on the ship steel.The manufacture of high quality ship steel at present is mainly through the role of the micro alloying element such as the Nb,Ti and combining the TMCP rolling technology.In recent years,with the improvement of steel cleanliness,more attention paid to the application of rare earth in steel.A large number of studies have shown that light rare earth elements can improve the organization of the steel and improve the comprehensive performance of steel.Based on E36 ship plate steel as the research object,through the way of feeding line in E36 of ship plate steel smelting in the process of feeding yttrium base of rare earth core,yttrium base of rare earth on E36 ship plate steel group performance and the influence of the phase change law.The specific research contents and conclusions are as follows:(1)The main effect of yttrium base rare earth on E36E36 Steel Phase Transformation: after the addition of yttrium base rare earth,E36 steel AC1 and AC3 respectively by 710 C and 875 C to 730 C and 885 C;bainite of E36 RE steel in tissues decreased;the organization of E36 RE steel under different cooling rate.The hardness decreased;the CCT curve of E36 RE steel with E36 steel has left,the transition temperature of bainite increased.(2)after adding Y-base of rare earths,the E36 E36 RE steel ball light volume increased,and free cementite is dispersion;And E36 R steel than E36 pearlitic steel lamella spacing,and pearlite performance for degenerate state.Rare earth elements in grain boundary defects such as partial poly and super-cooling degree of increase is a major cause of pearlite increases.After adding Y-base of rare earth,steel night super-cooling degree increase and solid solution of rare earth elements in steel,hindered the C atom diffusion,limiting the cementite nucleation speed and growth speed,refine the pearlitic structure.(3)the Y-base rare-earth E36 inclusions in steel by metamorphism.On the one hand is to the inclusion shape metamorphism,before adding rare earth inclusions in steel owner if CaO,Al2O3 metal inclusions and the MnS inclusions,such as adding Y-base of rare earth,inclusion into rare earth compound inclusions in steel.On the other hand is to improve the inclusion size,E36 transverse steel before adding rare earth inclusions are mainly about 20 microns long strips of MnS inclusions,after adding rare earth E36RE inclusions in steel is mainly for less than 5 microns within spherical rare earth compound inclusions.(4)The effect of Y-based rare earth on the impact toughness of E36 steel is improved,which is mainly reflected in the following aspects: the impact toughness is improved,especially the low temperature impact toughness.The difference of the longitudinal and transverse impact energy is reduced,the aspect ratio of impact energy is reduced,and the anisotropy is improved.The refinement of the microstructure and the modification of the inclusions are the main factors affecting the impact properties. |
