论文部分内容阅读
针对苏钢42CrMoAH钢大方坯(260mm×340mm)浇注存在的铸坯皮下夹杂物问题,分析了夹杂物的主要类型及其来源,研究了精炼渣组成对钢洁净度的影响,同时讨论了连铸工艺条件对铸坯皮下40mm以内的夹杂物数量、尺寸、组成的影响。研究表明:铸坯中的夹杂物主要来源于以A12O3为主的脱氧产物及以MnO·Cr2O3,FeO·Cr2O3等尖晶石类为主的二次氧化产物;由于精炼渣吸收A12O3夹杂物能力不足,再加上拉速低等因素导致结晶器内钢液上循环流弱,不利于脱氧及二次氧化产生的微小夹杂物在结晶器内碰撞聚合后上浮、排除,以致铸坯中尺寸为20~50μm的夹杂物达到总量的45%左右;采取提高精炼渣炉渣碱度、w(CaO)/w(Al2O3)值,及采用双侧孔型水口以加强结晶器内上循环流等措施后,铸坯皮下20~50μm的夹杂物降低了64%。
Aiming at the problem of subsurface inclusions in 42CrMoAH steel bloom (260mm × 340mm) in SuCong, the main types of inclusions and their sources were analyzed. The influence of refining slag composition on steel cleanliness was also discussed. Effect of technological conditions on the number, size and composition of inclusions within 40 mm of the cast slab. The results show that the inclusions in slab mainly come from the deoxidation products dominated by A12O3 and the secondary oxidation products dominated by spinel such as MnO · Cr2O3, FeO · Cr2O3. Due to the lack of ability of refining slag to absorb A12O3 inclusions , Coupled with the pulling speed and other factors lead to lower mold circulating fluid flow on the molten steel is not conducive to deoxidation and secondary oxidation of small inclusions bump in the mold after the collision polymerization, eliminating, resulting in slab size of 20 ~ 50μm inclusions reach about 45% of the total amount. After improving the slag basicity, w (CaO) / w (Al2O3) value and adopting double-side port to enhance the circulating flow in the mold , Inclusions 20 to 50 μm subcutaneously reduced by 64%.