钢水连续铸造的应用.docVIP

钢水连续铸造　　于功利　井上　健　安中弘行 (鞍山钢铁(集团)公司)　((株)神户钢所加古川铁所) 摘　要　为了定量把握结晶器中的钢水流动、钢水过热度及结晶器传热阻力对初期凝固坯壳的凝固不均一的影响，利用水冷铜板的浸渍实验，测定了各种铸造条件下的凝固坯壳厚度、凝固不均一度及树枝晶偏角；利用水力模型实验，并对实机铸坯的凝固组织分析，EPMA对负偏析带的线分析，得出了在结晶器中凝固坯壳上负偏析带的产生原因。其主要结果是：①随着钢水流动速度及过热度的增加，凝固坯壳厚度减少，凝固坯壳不均一度增大；②缓冷结晶器可有效地改善低碳钢初期凝固坯壳的不均一性；③在连铸坯表层(6～10 mm)存在的负偏析带产生于距弯月面250～450 mm处，其生成原因是由于浸渍水口的吐出流所致。关键词　连续铸造　钢水流动　过热度　凝固不均一度　负偏析带 EFFECT OF MELT FLOW ON INITIAL SOLIDIFIED SHELLOF CONTINUOUS CAST STRAND YU Gongli(Anshan Iron and Steel(Group) Co.)TAKESHI INOUE　HIROYUKI YASUNAKA(Kakogawa Works,Kobe Steel,Ltd.) ABSTRACT　To estimate quantitatively the effect of melt flow in mold and superheat as well as the mold heat transfer resistance,on the unevenness of initial solidified shell,the water cooled copper plate dipping test has been used to measure the thickness of solidified shell and dendrite angle under various casting conditions.The reason of white band formation in the solidified shell in the mold has been studied by means of water modeling test and the analysis of the solidified microstructure of practical CC slab and liner analysis of white band has been performed by EPMA.Main results are as follows:①The thickness of solidified shell decreases and the unevenness is increased with the increase of flow velocity and superheat of the melt;②Slow cooling mold can effectively reduce the unevenness of initially solidified shell of hypoperitectic steel;③The white band existing under the surface of CC slab(6～10 mm)is formed at 250～450 mm from meniscus,and resulted by the jet flow from submerged nozzle.KEY WORDS　continuous casting,melt flow,superheat,unevenness of initial solidified shell,white band 1　前言 　　关于钢水流动对连铸初期凝固坯壳的影响前人已有许多报告［1～5］。但是，钢水流动及过热度究竟对初期凝固坯壳不均一的形成，初期凝固组织中负偏析带的产生有如何影响，尚有许多不明之处。　　本研究利用水冷铜板的浸渍实验，测定了各种铸造条件下的凝固坯壳厚度、凝固不均一度及树枝晶偏角，分析了钢水流动、过热度及结晶器传热阻力对凝固不均一度的影响；利用水力模型实验及对实机铸坯的凝固组织观察，分析了结晶器内钢水的流动状态及负偏析带的形成原因。 2　实验方法及条件 　　实验装置的原理参见文献［6］。将200 mm×275 mm×70 mm的水冷铜板一边振动一边向钢水中浸渍，在钢水中停留10 s后，以300 mm/s的速度急速从钢水中把水冷铜板及凝固坯壳提取出来。为了模拟钢水对初期凝固