20CrMnTiH齿轮钢冶炼各工序夹杂物的演变规律OA

This study investigates the characteristics of inclusions in 20CrMnTiH gear steel produced via the process route of converter → refining → VD furnace → continuous casting.To further control the level of non-metallic inclusions,systematic sampling and analysis were conducted at each stage of the smelting process.The formation and evolution mechanisms of inclusions were explored in terms of their quantity,size,type,morphology,and composition.The results indicate that the primary inclusions at the LF refining entry stage are clustered Al2O3,which gradually transform into Al2O3-CaO-MgO complex inclusions by the LF exit stage.After VD degassing,the inclusions further evolve into Al2O3-CaO-MgO-CaS,with subsequent transitions between solid and liquid phases of calcium aluminate(CA)inclusions.Analysis reveals potential secondary oxidation phenomena during the stages from soft blowing to tundish casting and billet solidification,leading to an increase in oxide inclusions.Additionally,CaS begins to encapsulate the edges of oxide inclusions after VD degassing.Notably,TiN inclusions increase significantly from the tundish to the billet stage.Improvement measures are proposed to address the identified issues in this paper.