45号钢钢水洁净度的控制研究

Control of cleanliness of 45 Steel

南钢45号钢的主要问题是铸坯和轧材裂纹率高,轧材易在热墩或热墩后的机加工过程中出现不同程度的开裂。究其原因是由于钢中大量的氧化物和硫化物夹杂使得其塑性、韧性及疲劳强度降低、加工性能变坏所致。因此,通过控制转炉终点碳质量分数和出钢过程温度、增加软吹氩时间、在LF炉中提前造白渣以及加强保护浇注等措施,降低了45号钢钢中夹杂物的数量,有效的避免了加工开裂。

The main quality problem of 45 steel produced by Nanjing Steel is high crack rate of rolling products caused in the processes of hot forging or machining after hot forging.The reason is attributed to the existence of a large amount of oxide and sulfide inclusions in steel which result in low plasticity,toughness and fatigue strength,and finally bad processability.In order to avoid cracking formation in machining process,a series of measures were taken to reduce the quantity of inclusions in 45 steel.They included： controlling the content of end-point carbon and tapping temperature in BOF,extending soft blowing time,making white slag in LF in advance and enhancing protective casting,etc.As a result,the quantity of inclusions in 45 steel was reduced and cracking formation was avoided.