Study On The Behavior Of Inclusions In Bismuth-based Rare Earth Microalloyed E36 Slab

With large-scale,high speed of the ship and Marine resources development,put forward higher requirement for the comprehensive performance of high strength ship plate steel.Rare earth has been called the "industrial vitamin".At present a lot of metallurgy domestic and overseas researchers have confirmed some effect of rare earth in steel.Ganzhou is adjacent to Xin YU iron and steel companyand has abundant rare earth resources.Therefore,Rare earth has unique advantages in the application of the steel.The E36 plate ship prodected from Xinyu iron and Steel Company is regarded as the research object.The research will lead to Yttrium base Rare-earth on the influence of the inclusions in the E36 slab behaviors.The company prodect two furnace Yttrium base according to the normal production of E36 steel chemical composition and technological requirements,and without yttrium base Rare-earth E36 steel were analyzed.By optical microscope,scanning electron microscopy?sem?,energy spectrum and electro-dialysis research methods to analyze the Yttrium base Rare-earth impurity elements in liquid steel and inclusions in the slab,the influence of the organization,the specific research contents and conclusions are as follows:By the thermodynamic calculation,the results show that the inclusions is CaO-Al₂O₃-MgO-Ca S system in the E36 slab;In E36 RE slab,yttrium base Rare-earth has strong deoxidizing and desulfurizing ability;The production of rare earth inclusions order is that sulfur oxides of rare earth oxides,rare earth,rare earth sulfide,and are often the coexistence of a variety of rare earth inclusionsBy the electron microscopy and energy spectrum analysis showed that the main inclusions is CaO-Al₂O₃-MgO-CaS system in the E36 slab,consistent with the theoretical calculation;E36RE inclusions in the billet for?Y,Ce?₂O₃-?Y,Ce?AlO₃-Ca F-Ca S,?Y,Ce?₂O₂S-?Y,Ce?AlO₃-Ca F system etc.And the production of rare earth inclusions order is that sulfur oxides of rare earth oxides,rare earth,rare earth sulfide,consistent with the theoretical calculation;E36 inclusions in the billet is more irregular or globular,E36 RE globular inclusions in the slab is rules of the ball,show that rare earth inclusions can play effective metamorphism.More sulfur containing rare earth oxide inclusions are mainly distributed in the middle of the slab,More inclusions containing rare earth oxides are mainly distributed in the upper portion of the slab.Because the cerium inclusion density is larger than of yttrium,and rare earth composite inclusions Ce₂O₂ S quantity is more than the Y₂O₂ S,and the amount of Y₂O₃ is far more than that of Ce₂O₃,the amount of rare earth oxides is more than the rare earth sulfur oxides.By metallographic microscope and details electrolytic process show that adding yttrium base of rare earth to liquid steel to improve the effect of the size of inclusions in the slab is not obvious,but it can make the slab in the irregular globular inclusions were metamorphosed into rules of the ball.Yttrium base Rare-earths has strong strong deoxidizing and desulfurizing ability.The average deoxidization,desulphurization rate is as high as 51.88%,78.49%;UseONH-300 oxygen and nitrogen hydrogen tester determination results showed thatO,N,H content in E36 RE slab than E36 was respectively reduced by 39.74%,8.7% and 39.74%.Yttrium base of rare earth at the center of the billet segregation from the original 1.5 C to 0.5 C,and reduce the surface crack,refining the slab grain group,is expected to further improve the performance of the steel.