电渣重熔过程钢的洁净度控制

Control of steel cleanliness in electroslag remelting process

电渣钢的洁净度是影响其性能的关键,在实际生产中经常由于洁净度问题导致产品的质量不合格。本文分析了影响电渣重熔钢锭洁净度的主要因素和提高洁净度的技术手段。相关研究表明:渣料的磷主要来自萤石,大部分被还原而进入钢中,采用含BaO渣系可以抑制甚至能部分去除钢中的磷;气相氧化脱硫是电渣重熔工艺的一个主要特点,因此在氩气保护下会明显减少脱硫效果,渣中添加CaO组元有利于电渣重熔过程的脱硫;钢中的氢主要来自渣料和大气,因此采用预熔渣和干燥气体保护可以有效控制钢锭增氢;氩气保护和防止电极与渣面拉弧对避免钢锭增氮有一定的作用;电渣重熔过程中自耗电极表面氧化产生的氧化铁皮是氧的主要来源,因此电极表面采用防氧化涂层、惰性气体保护是降低钢中氧含量和氧化物夹杂数量的有效措施,同时减少渣中的不稳定氧化物FeO、MnO、SiO2含量,提高炉渣碱度,可有效地降低钢中的氧含量和氧化物夹杂数量。

The cleanliness of electroslag remelting(ESR)steel is a key factor influencing its performance in practical applications,and disqualification of the products is usually due to the cleanliness problems.In this article the main factors influencing the ESR ingot cleanliness and the technical measures to improve the steel cleanliness are discussed in detail.Related research results show that phosphorus in slag mainly comes from fluorite,and most of the phosphorus can be reduced and dissolved into steel.Nevertheless,using BaO-bearing slag can inhibit phosphorous dissolution and even partly remove phosphorus out of the steel.Gas phase oxidative desulfurization is one of the main characteristics of the ESR process,and thus the desulfurization effect will be significantly reduced under argon protection.Moreover,addition of CaO to the slag can promote the desulfurization in ESR process.Hydrogen in ESR ingot,which is mainly from slag and atmosphere,can be effectively controlled by using pre-melted slag with low hydrogen permeability and under dry atmosphere.Argon protection and prevention of arcing between electrode and slag surface can to a certain extent avoid the increase of nitrogen content in the ingot.The iron scale generated on consumable electrode surface by oxidation in the ESR process is the main source of oxygen,and thus inert gas protection is the most effective measure to reduce the content of oxygen and oxide inclusions in steel.In addition,lowering the contents of unstable oxides such as FeO,MnO and SiO2 in the slag and raising the basicity of the slag can effectively reduce the content of oxygen and the number of oxide inclusions in steel.