管线钢冶炼过程夹杂物控制

Inclusions control of pipeline steel in steelmaking process

针对某钢厂采用"BOF→LF→RH"工艺流程生产的高级别管线钢,通过金相、扫描电镜、能谱等手段分析了钢中夹杂物,并从热力学角度进行了研究。结果表明当钢中的w(AlS)=0.025%,若钙处理时钢中w(CaO)>18×10-6,w(S)<0.011%,可较易地将Al2O3夹杂变性为低熔点的C12A7。研究后提出一系列工艺优化措施:强化转炉顶底复合吹炼工艺、改善吹氩站和LF的吹氩制度、调整精炼渣系使w(CaO)/w(SiO2)控制在4.5～6.0,w(CaO)/w(Al2O3)控制在1.7～1.9,最终钢水w(S)可控制在0.000 8%以下,氧化物和硫化物的夹杂物级别控制在1.0级以内。

The high grade pipeline steel produced in a specific steel work by the BOF→LF→RH process route is investigated. The inclusions in the steel are examined and analyzed by application of certain analytical techniques such as metallographic examination、SEM and EDS and then the mechanism of formation of the inclusions is studied according to the thermodynamics. Results show that when the w（AlS） is about 0.025 % the inclusion Al2O3 in steel can be easily modified to low melting point C12A7 if w（CaO）〉18×10-6,w（S）〈0.011 % in the steel. A series of technological measures have been put forward such as intensification of the topbottom combined blown process of the converter, improvemnt in the argon blow scheme in both the argon blow station and LF facility and adjustment of the refining slag series so as to control w（CaO）/w（SiO2） within the limit of 4.5 to 6.0 and w（CaO）/w（Al2O3） in 1.7 to 1.9and finally control w（S） in below 0.000 8 %and confine the grade of oxide and sulfide inclusions in grade 1.0in steel.