X80管线钢板中条串状CaO-Al_2O_3系非金属夹杂物的控制  

CONTROL OF STRING SHAPED NON-METALLIC INCLUSIONS OF CaO-Al_2O_3 SYSTEM IN X80 PIPELINE STEEL PLATES

作　　者：王新华[1] 李秀刚[1] 李强[1] 黄福祥[1] 李海波 杨建[2] 

机构地区：[1]北京科技大学冶金与生态工程学院,北京100083 [2]首钢技术研究院,北京100042

出　　处：《金属学报》2013年第5期553-561,共9页Acta Metallurgica Sinica

基　　金：国家重点基础研究发展计划资助项目2010CB630806~~

摘　　要：采用转炉-钢包精炼炉-RH真空精炼钙处理炼钢工艺生产的X80管线钢板中,条串状B类夹杂物主要为低熔点CaO-Al_2O_3系,其成因主要为:(1)炉外精炼和钙处理后,钢液中存在许多微小CaO-Al_2O_3系液态夹杂物,连铸过程聚集成较大尺寸夹杂物(10-20μm).轧制过程中变形为大型条串状夹杂物.(2)尺寸较大的夹杂物在钢液钙处理时,外表层转变为高熔点CaO,CaS或CaO-CaS系,但内部仍为低熔点的CaO-Al_2O_3系,此类夹杂物在钢板轧制时,内部仍能够变形,最终延展为条串状夹杂物.对X80管线钢板B类夹杂物的控制采用新的策略,将控制重点由钢液钙处理后去除低熔点CaO-Al_2O_3系夹杂物,改为在钙处理前强化去除钢液中夹杂物,尤其是较大尺寸的夹杂物.采取新控制策略后,真空精炼后夹杂物数量大幅度降低,钙处理效果显著提高,钢板中检测到的夹杂物全部为高熔点CaO-CaS系夹杂,B类夹杂物评级由以往低于2.0级降低至0级.The string shaped B type non-metallic inclusions in API （American Petroleum Institute） X80 pipeline steel plates, produced by the BOF-LF RH-Ca treatment steelmaking route, were mainly of CaO-Al2O3 system with lower melting temperatures. The formation reasons are as follows： （1） there existed many small sized liquid inclusions 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 string shaped inclusions in steel plates during rolling. （2） for the larger sized and 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 remained to be CaO-Al2O3 system. During rolling, these inclusions could also be elongated to string typed ones because of their soft CaO-Al2O3 centers. A new strategy for control of B type inclusions in X80 pipeline 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 remove as much as possible inclusions especially large sized inclusions before the Ca treatment. With the new strategy, the amount of inclusions after RH refining was remarkably decreased and the efficiency of Ca treatment significantly improved. The non metallic inclusions found in steel plates were all of high melting temperature CaO-CaS system and the severity of B type inclusions has been lowered from ≤2.0 to 0.

关 键 词：X80管线钢 非金属夹杂物 B类夹杂物 二次精炼 钙处理 

分 类 号：TF777[冶金工程—钢铁冶金]