Control of stringer shaped non-metallic inclusions of CaO-Al2O3 system in API X80 linepipe steel plates
- 作者：WANG XinhuaHUANG FuxiangLI QiangLI HaiboYANG Jian
- 会议时间：2013-06-01
- 关键词：linepipe steel plate ; non-metallic inclusions ; B type inclusions ; Ca treatment
- 作者单位：WANG Xinhua,HUANG Fuxiang(School of Metallurgical and Ecological Engineering,University of Science and Technology Beijing,Beijing 100083,China)LI Qiang(Research Institute,Nanjing Iron and Steel Corporation,Ltd.,Nanjing 210035,Jiangsu,China)LI Haibo,YANG Jian(Technical Research Institute,Shougang Corporation,Ltd.,Beijing 100042,China)
- 母体文献：第五届宝钢学术年会论文集
- 会议名称：第五届宝钢学术年会
- 会议地点：上海
- 主办单位：中国金属学会
- 语种：chi
摘要
The stringer shaped B type non-metallic inclusions in API X80 linepipe steel plates produced through " BOF-LF-RH-Ca treatment" steelmaking route were found mainly of CaO-Al2O3 system with lower melting temperatures,which formed because: ① There existed many small sized liquid inclusions of CaO-Al2O3 system in liquid steel after the secondary refining and Ca treatment.These small inclusions could aggregate to larger ones of 10 - 20 μm in continuous casting and be deformed into stringer shaped inclusions in steel plates during rolling.②The larger sized low melting temperature CaO-Al2O3 inclusions,in Ca treatment,their surface layers could be modified into high melting temperature CaO,CaS or CaO-CaS system,but the centers were still of CaO-Al2O3 system.During rolling,these inclusions could also be elongated to stringer typed ones because of their soft CaO-Al2O3 centers.A new strategy for control of B type inclusions in linepipe steel plates was adopted.The key of the control was shifted from removing low melting temperature inclusions of CaO-Al2O3 system after Ca treatment to removing as much as possible inclusions especially large sized inclusions before the Ca treatment.With the new strategy,amount of inclusions after RH refining was remarkably decreased and the efficiency of Ca treatment significantly improved.The inclusions found in steel plates were all of high melting temperature CaO-CaS system and the severities of B-type inclusions have been lowered from "≤2.0" to "0".