电流强度对电渣重熔304不锈钢中夹杂物特征的影响

利用实验室规模电渣炉在大气气氛下重熔304不锈钢,考察了不同电流强度(1500、1800、2100A)下电渣锭中夹杂物的特征及全氧含量、硫含量变化,并对钢中硫化物的析出行为进行了热力学分析。结果表明,电渣重熔过程可以有效去除钢中的夹杂物,但随着电流强度的增大,电渣锭的全氧含量和硫含量增加,夹杂物数密度及尺寸增大,电渣锭的洁净度恶化。当电流强度较低(1500A)时,电渣锭中夹杂物主要是以氧化铝为核心、外表裹有硫化物的双层结构,未发现单个的(Mn,Cr)S夹杂;而1800A和2100A重熔时,电渣锭中不仅有以Al-Si-Ca-Ti-Cr-Mn氧化物为核心、外围包裹着(Mn,Cr)S的双层结构夹杂,而且由于电渣锭中硫含量高和凝固过程中残余液相中溶质的富集,其中还有单个(Mn,Cr)S夹杂物存在。本试验条件下,在1500A下重熔更有利于提高304不锈钢电渣锭的洁净度。

Effect of current intensity on the inclusion characteristics in 304 stainless steel during the electroslag-remelted process

In this paper, a laboratory-scale electroslag furnace was applied to remelt 304 stainless steel under open atmosphere. The characteristics of inclusions as well as the total oxygen content and sulfur content in the electroslag ingots under different current intensities (1500,0, 2100 A) were investigated, and the thermodynamic analysis of sulfide precipitation in steel was also carried out. The results show that, the electroslag remelting (ESR) process can effectively remove the inclusions in steel. However, with the increase of current intensity, the total oxygen content and sulfur content in ESR ingot increase, the number density and size of the inclusions also rise, which results in the further deterioration of ingot cleanliness. At the low current intensity of 1500 A, the inclusions have a two-layer structure with alumina as the core covered with sulfide, and no separate (Mn,Cr)S inclusion is observed; while at the higher current intensities of 1800 A and 2100 A, in the ESR ingots are found not only the complex inclusions with Al-Si-Ca-Ti-Cr-Mn oxide as the core which are surrounded by (Mn,Cr)S but also the single (Mn, Cr)S inclusions precipitated due to the higher sulfur content and solute segregation. In the present study, remelting at a current density of 1500 A is more conducive to improving the cleanliness of the ESR ingot.