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通过系统取样跟踪分析了BOF-LF-圆坯连铸工艺生产20Mn2钢的洁净度限制环节;结果表明,凤宝20Mn2钢洁净度的限制性环节是二次氧化。明显的二次氧化发生在3个位置:喂Si-Ca线后;LF结束到中间包过程;中间包到结晶器的浇注过程。从入LF到浇注结束整个过程N质量分数平均增加40×10-6,累积二次氧化量达到109×10-6,夹杂物总去除量为198×10-6;大型夹杂物在喂Si-Ca线和中间包中均有明显增加,主要为Al-Si-Mn-Ti复合氧化物,是典型的二次氧化产物。因此,目前该厂改善洁净度的关键是保护浇注的控制。
The cleanliness limitation of 20Mn2 steel produced by BOF-LF-billet continuous casting process was analyzed through systematic sampling and tracking. The results showed that the limiting part of the cleanliness of Fengbao 20Mn2 steel was secondary oxidation. Significant secondary oxidation occurred in three locations: feeding Si-Ca line; LF end to the tundish process; tundish casting process. From the beginning of LF to the end of pouring, the mass fraction of N increased by 40 × 10-6 on average, the cumulative secondary oxidation reached 109 × 10-6, and the total removal of inclusions was 198 × 10-6. Large inclusions in the Si- Ca wire and tundish are significantly increased, mainly Al-Si-Mn-Ti composite oxide, is a typical secondary oxidation products. Therefore, the key to improving the cleanliness of the plant today is to protect the pouring control.