Study On The Influence Of Different Dearsenicization Methods On Inclusions In Arsenic-containing Welding Rod Stee

A large number of scrap steel is used in the production process of modern steel enterprises,which inevitably brings impurities such as arsenic into the steelmaking process.The presence of harmful element arsenic in steel will seriously affect the performance of steel products.This article studies the evolution of inclusions in different calcium based alloys,rare earth lanthanum,cerium,and neodymium during the arsenic removal process in molten steel using H08-3 welding rod steel as the research object through experiments and thermodynamic calculations.The arsenic removal mechanism of these arsenic removal agents is also discussed.Research has found that rare earth elements and calcium can not only purify molten steel through deep deoxidation and desulfurization,but also react with the residual element arsenic in steel to improve the occurrence form of arsenic in the steel.The results of using three types of calcium based alloys for arsenic removal show that adding calcium aluminum alloy has the best arsenic removal effect,with an arsenic removal rate of 56.36%;And the surface density of inclusions is the smallest and the distribution is the most uniform.Through thermodynamic discussions,it was found that the critical calcium content for arsenic removal reaction is 0.0037%,and the ultra-low control of oxygen and sulfur content is the key to achieving good arsenic removal effect.When the arsenic removal reaction occurs in molten steel,the oxygen and sulfur concentrations in equilibrium with calcium areω[O]=0.0012%ω[S]=0.00548%.When using rare earth lanthanum for steelmaking arsenic removal,adding 0.44%lanthanum to the molten steel has the best arsenic removal effect,with the highest arsenic removal rate of 85.55%;The typical forms of arsenic containing rare earth inclusions in steel are mainly La-As,La-O-As,and La-O-S-As system inclusions.The highest arsenic removal rate is 87.27%when 0.32%cerium is added,and the forms of rare earth inclusions containing arsenic are mainly spherical and ellipsoidal Ce-As and Ce-O-As.The addition of 0.302%neodymium has the highest arsenic removal rate of 69%for molten steel.Arsenic containing rare earth inclusions are mainly spherical and ellipsoidal Nd-As,Nd-O-As,and Nd-O-S-As system inclusions.The use of calcium alloys and rare earths can also change the quantity,size,distribution uniformity,and surface density of inclusions in steel,playing a role in modifying inclusions.Through thermodynamic calculations,it was found that the approximate order of formation of La containing inclusions in steel is La₂S₃,Al La O₃,La Al₁₁O₁₈,La S,La₂O₃,Al₇La₃₃O₆₀,and La-S-As.The approximate generation order of Ce containing inclusions in steel is Ce₂O₃,Al₁₁O₁₈Ce,Al Ce O₃,Ce₃S₄,Ce₂O₃,Ce S,and Ce₂C₃.When Nd is added to the molten steel,inclusions that may be generated include Al₂O₃,Al Nd O₃,Al₁₁O₁₈Nd,Al₂Nd₄O₉,and Nd₂O₃.