100 t LD-LF-RH-CC流程冶炼60Si2Mn弹簧钢非金属夹杂研究

试验60Si2Mn弹簧钢（/%:0.58C,1.75Si,0.75Mn,0.012P,0.005S,0.006Als,0.008Alt）的工艺流程为100t转炉不加铝饼脱氧,采用硅铁脱氧,控制终点C]≥0.08%,出钢温度1620～1660℃,LF到站温度≥1500℃,精炼时间不少于35min,RH真空度≤100 Pa并且保持时间≥20 min,软吹前喂入硅钙线100 m进行变性夹杂物处理,150 mm方坯采用全程保护浇铸。分析结果表明,钢中氧含量在RH精炼过程中到达最低,在中间包阶段又有所回升。在LF精炼中,钢液增氮明显。夹杂物成分以Al₂O₃、SiO₂、MgO和CaO为主,在LF精炼过程中,SiO₂含量下降了26.7%,MgO和CaO含量上升了36.7%,最终铸坯中夹杂物成分为33%Al₂O₃,20.7%SiO₂,45%MgO和CaO,减少了钢中高硬度夹杂物的含量。

Study on Nonmetallic Inclusions in Spring Steel 60Si2Mn Produced by 100 t LD-LF-RH-CC Flow Sheet

The production process of tested spring steel 60Si2Mn(/% ：0.58C, 1.75Si,0.75Mn,0.012P,0.005S, 0.006Als ,0.008Alt)is not adding aluminum cake but adding ferrosilicon to deoxidize in an 100 t converter, controlling end C]≥0.08% ,and tapping liquid temperature 1620 ?1660℃,LF original temperature ≥ 1500℃ ,refining time no less than 35 min,RH vacuum ≤100 Pa for，20 min,feeding 100 meters of calcium and silicon wire for modification of inclusions before soft blowing, in whole process shielding-atmosphere casting 150 nun square billet. Analysis results show that the oxygen content in steel reaches the lowest in RH refining process, and rises in tundish stage. In LF refining process, the nitrogen increase of liquid steel is obvious. Inclusions are mainly composed of A12O3 ,SiO2 ,MgO and CaO. During LF refining, the content of SiO₂ decreases to 26.7% , while the content of MgO and CaO increases to 36.7%. Finally, the inclusions in the casting billet are 33% Al₂O₃,20.7% SiO₂ and 45% MgO and CaO to decrease the high hardness inclusions in steel.