Effect of physical properties of slag on sulphur removal mechanism during ESR process

In this study, the effect of slag's physical properties on the desulphurization process in electroslag remelting (ESR) was investigated. Three different steel grades were used as consumable electrodes in ESR. Each steel was remelted under three slag compositions with different physical and chemical properties. The results obtained showed the efficiency of ESR in removal of up to 68 % of the sulphur contained in the metal. This pronounced effect of ESR on desulphurization is a result of slag/metal and gas/slag reactions. Although the greatest portion of sulphur is removed by gas/slag reaction which is enhanced by using a low viscosity slag, the metal/slag reaction represents the rate controlling step over all the desulphurization process. Slag/metal reaction occurring at the metal droplets/slag interface is the most effective and enhancing by relatively high slag viscosity and high CaO content in the slag. Slag composition (mass contents in %) of 70 CaF₂, 15 CaO and 15 Al₂O₃ has a good combination of chemical reactivity and physical properties for attaining the highest degree of desulphurization among the three investigated slags.     

渣成分对高温合金0Cr15Ni25Ti2MoAlVB 电渣重熔Ti烧损率和钢锭表面质量的影响

试验分析了2.5 t电渣炉使用4种成分熔渣重熔0Cr15Ni25Ti2MoAlVB合金时的Ti烧损率。试验结果表明,4种渣系中75%CaF₂-15%Al₂O₃-10%CaO三元提纯渣的Ti烧损率最低,为7.0%,并且避免了70%CaF₂-30%Al₂O₃的二元渣系重熔钢锭表面渣沟等缺陷。     

Effect of the Slag Composition and a Protective Atmosphere on Chemical Reactions and Non‐Metallic Inclusions during Electro‐Slag Remelting of a Hot‐Work Tool Steel

The remelting behavior of the hot‐work tool steel X37CrMoV5‐1 is investigated with several experimental melts on a lab‐scale ESR‐plant. The investigated parameters comprise a variation of the slag compositions and the use of a protective nitrogen atmosphere. Variations of the slag composition include slags with different contents of CaF₂, CaO, and Al₂O₃ as well as a variation of the SiO₂‐content in the slag. The remelted ingots are forged and analyzed regarding their chemical composition. The distribution and composition of the non‐metallic inclusions (NMI) is studied by an automated SEM‐EDX method. Additionally, the chemical composition of the slag after remelting is analyzed. The results show clearly an equilibrium reaction between Si and Al in the steel with SiO₂ and Al₂O₃ in the slag as well as the effect of oxygen in open ESR operation. A protective atmosphere reduces the Si‐losses during remelting, but has no major effect on the number or composition of NMI compared to open remelting. The content of NMI, especially the larger ones, is reduced significantly in all remelting experiments. The majority of the NMI are MA‐spinel type except for the CaO‐free slag, where alumina inclusions prevail. In general, remelting leads to an almost complete removal of sulfides, a reduction of oxisulfides, and a slight increase of oxides.     

酸性渣SiO2含量对电渣重熔S-Pb-Te易切削不锈钢冶金质量的影响

通过500 kg保护气氛电渣炉试验研究三元渣（/%:65CaF2,25Al2O3,5SiO2）、四元渣（/%:55CaF₂,20Al₂O₃,20SiO₂,5CaO）和五元渣（/%:45CaF₂,20Al₂O₃,25SiO₂,5CaO,5MgO）对S-Pb-Te易切削不锈钢（/%:1921 Cr,1.52.5Mo,0.10.3Pb,0.250.40S,0.030.10Te）电渣锭冶金质量的影响。结果表明,四元渣和五元渣S收得率较三元渣高;三元渣Pb收得率相对较高;3种渣系Te收得率无明显差异;含SiO₂为25.0%的五元渣系,所重熔的S-Pb-Te易切削不锈钢电渣钢锭小头和大头S、Pb和Te偏差最小,分别为△S 0.03%、△Pb 0.02%和△Te0.028%,且电渣钢锭表面质量良好。