EAF-RH-LF-CC生产Q345B的洁净度研究

Study of the Cleanness of Q345B Seamless Steel under Process of EAF-RH-LF-CC

在炼钢过程各工位取样,分析研究了EAF-RH-LF-CC工艺下Q345B无缝管钢的洁净度。试验结果表明:(1)铸坯中的总氧质量分数可以稳定在0.002%左右;(2)非金属夹杂物以近似球形的氧化物和硫化物居多,其数量依炼钢流程工序不断降低,且精炼过程中降幅最大。(3)LF过程有明显的增氮现象,需控制LF过程的二次氧化;(4)与RH过程相比,在LF结束时钢中10～20μm的夹杂数量较多,应适当延长LF脱氧后的软吹时间:(5)RH精炼初渣中w(FeO+MnO)过高,RH钢包渣需进行改质处理。

The purity of Q345B seamless steel have been studied by during the EAF-RH-LF-CC technological process. Results show that： sampling and analyzing at each station, which had been produced （ 1 ） total oxygen content of slabs can be controlled around 0.002%; （2） non-metallic inclusions main shape nearly like a circle and consist of oxides and sulfides in the whole routes of steel production. The number of non-metallic inclusions in steel continue to reduce following the process of steel making and there was the largest drop in refining process; （3） the nitrogen content remarkable increased between LF refining process and continue casting process, so the liquid steel should have prevented from secondary oxidated; （4） after the LF refining, the number of non-metallic inclusions in size of 10μm-20μm were larger, which have been compared with the end of RH refining. Therefore the weak agitation by Ar blowing should be protensive after de- oxidation under the LF refining; （5） w （FeO ＋ MnO） was so high in the workingslag of RH refining that the slag needs to be deoxidated.