Research On The Modification/shape Of B-type Non-metallic Inclusions In High Carbon Hard Wire Steel By Rare Earth

This paper studies the effect of rare earth addition on the number,size and average size of alumina inclusions in SWRS82B steel.The experimental results were verified by thermodynamic calculations and evolution analysis,and the evolution of alumina inclusions after the addition of rare earth elements was analyzed.Observe the three-dimensional specific morphology of the surface of inclusions by non-aqueous electrolysis.The experimental results show that before adding cerium,the size of the inclusions is in the range of 8.65μm-11.32μm,and the shape was irregular.After the addition of cerium,the inclusion size in the molten steel was reduced by 5.13-6.48μm,and the inclusions gradually became spherical.And the modification way of Al₂O₃inclusions in SWRS82B steel was:Al₂O₃→Ce₂S₃+Ce Al O₃+Ce₂O₂S+Al₂O₃→Ce₂S₃+Ce Al O₃+Ce₂O₂S/Ce₂S₃+Ce₂O₂S→Ce₂S₃+Ce₂O₂S.The calculation results of the edge-to-edge matching model show that Ce₂O₂S preferentially nucleates heterogeneously on Al₂O₃,andγ-Fe preferentially nucleates heterogeneously on Al₂O₃.With the increase of lanthanum addition,the inclusion size in molten steel decreased by 5.9-7.7μm after modification.By increasing the amount of lanthanum added,the way to modify Al₂O₃ inclusions in steel was as follows:Al₂O₃→La Al O₃+La₂O₃·11Al₂O₃+La₂S₃→La Al O₃+La₂O₂S+La₂S₃→La₂S₃+La₂O₃.The calculation results of the edge-edge matching model show that La S preferentially nucleates heterogeneously on Al₂O₃.With the increase of yttrium addition,the inclusion size in molten steel decreased by 6.9-8.6μm after modification.The way to modify Al₂O₃ inclusions in steel was as follows:Al₂O₃→Y₂S₃+YAlO₃+Al₂O₃→Y₂S₃₊YAlO₃+Y₂O₂S+YAlO₃+Al₂O₃→Y₂S₃+Y₂O₂S.The collisions between small particle inclusions（<1μm）in molten steel are mainly Brown collisions.Large-particle inclusions（>2μm）are mainly Stokes collisions.When the size difference between the two inclusions was larger,the Stokes collision frequency value was larger.The collision growth and floating between the inclusions will transform the originally large-sized alumina inclusions into small-particle rare-earth composite inclusions.Through the above theoretical and experimental studies,it is found that the modification effect of rare earth yttrium on alumina inclusions is the best,followed by rare earth lanthanum,and the modification effect of rare earth cerium is the worst.