16MnDR容器钢120t LF-RH-CC过程的洁净度研究

Study on Cleanliness of 16MnDR Steel for Vessel during 120t LF-RH-CC Steelmaking Process

通过LF、RH精炼和连铸过程对钢水和炉渣取样,对两炉16MnDR钢冶炼各阶段的T[O]含量和显微夹杂物的数量、尺寸及类型的变化进行了系统研究。结果表明:从LF进站→LF出站→RH破真空→钙处理→软吹→中间包浇注→轧材,两炉16MnDR钢中T[O]含量总体呈降低的趋势,其轧材中w(T[O])分别为0.001 4%、0.002 3%,达到其控制要求(w(T[O])≤0.003 0%)。造成16MnDR轧材中夹杂物评级超标的大颗粒夹杂物主要为链状12CaO·7Al 2O 3夹杂、近球形MgO·Al 2O 3尖晶石和不规则Al 2O 3夹杂,其中12CaO·7Al 2O 3夹杂为钙处理产物,MgO·Al 2O 3夹杂主要为钢中酸溶铝和耐火材料中MgO的置换反应产物,不规则Al 2O 3夹杂主要来源于浸入式水口部位的耐火材料。

Variations of the total oxygen content,amount,size and morphology of micro-inclusions in different stages of two heats of 16MnDR steels were systematical studied by sampling in molten steel and slag during LF and RH refining and continuous casting processes.The results showed that the total oxygen contents in two heats of 16MnDR steels were overall decreased in the process as:start of LF refining→end of LF refining→RH refining→calcium treatment→soft argon stirring→tundish pouring→hot rolling;and that the total oxygen content in the rolled products of two 16MnDR steels were 0.001 4%and 0.002 3%by mass,respectively,which reached the control requirement(w(T[O])≤0.003 0%).The larger inclusions in the rolled products,exceeding allowable level,were mainly chain-like 12CaO·7Al 2O 3 inclusions,nearly spherical MgO·Al 2O 3 spinels and irregular Al 2O 3 inclusions,of which 12CaO·7Al 2O 3 inclusions were calcium treated product,MgO·Al 2O 3 spinels were mainly the product of displacement reaction between acid-soluble aluminum and MgO in refractories,irregular Al 2O 3 inclusions were mainly derived from the refractories at submerged nozzle.