改善齿轮钢8620RH洁净度的生产实践

Production Practice on Improving Cleanliness of Gear Steel 8620RH

某钢厂的生产数据为实践依据,以改善汽车齿轮钢8620RH的洁净度为目的。采用EAF-LF-VD-CC短流程工艺冶炼汽车齿轮钢8620RH。在原技术攻关过程中发现提高精炼炉渣碱度有助于降低钢液氧含量,但伴随着精炼炉渣粘度增加,影响了夹杂物除去效果,导致连铸水口结瘤,反而恶化了钢液洁净度。通过控制电炉终点的钢液氧含量、温度以及炉后的预脱氧效果,实现供LF到站炉渣为“白渣”状态,为降低氧含量创造初始条件。通过调整电炉炉后的渣料配比和脱氧剂加入量,使精炼炉渣成分达到设定目标。重点是采取了合理的造渣操作提高精炼炉渣流动性,并在VD处理之后执行软吹操作。最终在实现了钢材氧含量8×10^(-6)以下,夹杂物检验B细≤1.5级、B粗≤0.5级的控制水平,稳定了产品质量。

On the basis of actual production data in a steelmaking plant,the objective is to improve cleanliness of automobile gear steel 8620RH.The short process steelmaking process,EAF-LF-VD-CC,was adopted to smelting automobile gear steel 8620RH in FuSteel.Increasing the basicity of refining slag is helpful to reduce the oxygen content in molten steel was been found in the process of the original technology research,but the viscosity of refining slag was increased.The effect of inclusion removal was affected,which cause nozzle clogging of continuous casting.The cleanliness of molten steel was deteriorated.Though controlling the oxygen content,temperature in molten steel at the end of EAF,and pre-deoxidation effect after EAF,to achieve white slag at initial stages of LF.This was created initial conditions for reducing oxygen content.The refining slag composition reaches set target by adjusting the slag ratio and the amount of deoxidizer added after EAF.The reasonable slagging operation was carried out to improving the fluidity of refining slag.The soft blowing operation is performed after VD treatment.The product quality was stable,the average oxygen content is below 8×10^(-6),B thin series rating of inclusion is no more than 1.5 and B coarse series rating of inclusions is less than or equal to 0.5 were achieved.