低真空对电渣重熔工艺和铸锭质量的影响

Effect of Low Vacuum on Electroslag Remelting Process and Ingot Quality

脱氧和夹杂物控制是电渣重熔钢锭质量提升的关键.分别在氩气保护的常压和低真空(10 kPa)条件下重熔H13电极,结合热力学计算,分析了低真空对电渣重熔工艺过程和铸锭质量的影响.结果表明,相比常压,低真空条件下渣池含气率升高,熔速波动更剧烈,所得电渣锭表面质量较差.常压和低真空条件制得电渣锭中总w_(O)分别为24×10^(-6)和18×10^(-6),碳脱氧反应随压力降低而加强,并逐渐取代铝脱氧.相比Al-O平衡,10 kPa条件下与电极中w_(C)平衡的溶解w_(O)更低,因而能够进一步降低钢锭中w_(O).碳脱氧产物是CO气体,不会引入新的夹杂物.常压和低真空条件制得电渣锭中夹杂物的类型没有明显区别,最大夹杂物尺寸从14.9μm分别减小到10.5μm和8.3μm,等效直径小于3μm的夹杂物检出比分别为63.85%和75.91%.低真空条件能够进一步细化夹杂物,提高钢锭洁净度.

Deoxidation and inclusions control are the key to improve the quality of ingots produced by electroslag remelting(ESR).The effect of low vacuum on the ESR process and ingot quality was experimentally studied in combination with thermodynamic calculations.H13 electrodes were remelted under argon protection at atmospheric and low vacuum(10 kPa)conditions,respectively.The results show that,compared with atmospheric pressure,a higher gas content in the slag pool,more drastic fluctuations of the electrode melting rate,and a rougher surface of the ESR ingot were observed under low vacuum.The total w O in the ESR ingots remelted under atmospheric and low vacuum conditions are 24×10^(-6)and 18×10^(-6),respectively.The carbon deoxidation reaction is greatly enhanced under low vacuum and gradually replaces aluminum deoxidation as the pressure decreases.Compared with Al-O equilibrium,the dissolved w_(O)in molten steel equilibrated with w_(C)of the electrode at 10 kPa is much lower.Thus,lowering pressure can further reduce the w_(O)of the ingot.Carbon deoxidation,of which the product is CO gas,will not introduce new inclusions.The pressure has little effect on the type of inclusions in ESR ingots.The biggest inclusions in the ESR ingots remelted under atmospheric and low vacuum conditions decrease from 14.9μm to 10.5μm and 8.3μm,respectively.The ratio of the detected inclusions with equivalent diameters less than 3μm are 63.85%and 75.91%,respectively.ESR under low vacuum condition can further refine the inclusions and improve the cleanliness of ESR ingots.