白云鄂博矿铌钛资源冶炼BT700L钢合金化工艺研究

Research on BT700L Steelmaking and Alloying Process by Using Niobium and Titanium Resources in Bayan Obo Mine

通过FactSage热力学软件计算和实验室25 kg真空感应炉冶炼BT700L汽车大梁钢,探讨精炼渣对铌钛合金化的影响规律,并研究稀土铌钛复合合金的加入对钢组织、夹杂物、析出物的影响。结果表明,55%CaO~25%Al_(2)O_(3)~15%SiO_(2)~5%MgO,碱度为3.7的精炼渣更加适合BT700L汽车大梁钢的冶炼。添加该精炼渣后,钢水中的Ti和渣中的SiO_(2)反应,Si被还原进入钢中,钢中Ti含量减少,Si含量提高;实验钢的铸态组织由铁素体和少量贝氏体组成;稀土的加入降低了钢中夹杂物的数量和尺寸,并使钢中析出物更加弥散细小。

Through FactSage thermodynamics software calculation and laboratory 25 kg vaccum-induction furnace smelting of BT700 L automobile beam steel,the influence law of refining slag on the alloying of niobium and titanium is discussed and the effect of the addition of rare earth niobium-titanium composite alloy on steel structure,inclusions and precipitates is studied.The results show that the 55% CaO~25% Al_(2)O_(3)~15% SiO_(2)~5% MgO refining slag with a basicity of 3.7 is more suitable for the smelting of BT700 L automobile beam steel.After the refining slag added,Ti in the molten steel reacts with SiO_(2) in the slag,Si is reduced into the steel,the Ti content in the steel decreases,and the Si content increases;The cast structure of the experimental steel is composed of ferrite and a small amount of bainite;The addition of rare earths reduces the number and size of inclusions in the steel,and makes the precipitates in the steel more dispersed and finer.