钛铌微合金钢连铸坯角部横裂纹敏感性  

Corner transverse crack sensitivity of Ti-Nb micro-alloyed steel slabs during continuous casting

作　　者：杨柳[1,2,3] 李阳 薛正良[1,2] 程常桂[1,2] YANG Liu1,2,3, LI Yang1,2, XUE Zheng-liang1,2, CHENG Chang-gui1,2(1. Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081, Hubei, China; 2. Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking, Wuhan University of Science and Technology, Wuhan 430081, Hubei, China; 3. Steelmaking Plant of Wuhan Iron and Steel Corporation Limited, Baowu Steel Group, Wuhan 430083, Hubei, China)

机构地区：[1]武汉科技大学钢铁冶金及资源利用省部共建教育部重点试验室,湖北武汉430081 [2]武汉科技大学钢铁冶金新工艺湖北省重点试验室,湖北武汉430081 [3]宝武集团武汉钢铁有限公司炼钢总厂,湖北武汉430083

出　　处：《钢铁研究学报》2018年第10期807-815,共9页Journal of Iron and Steel Research

基　　金：国家自然科学基金资助项目(51474163);青年科学基金资助项目(51504172)

摘　　要：为明确不同速度冷却时表面奥氏体的长大规律和在第Ⅲ脆性区的热塑性,用Gleeble-3500热模拟机分别对钛铌微合金钢进行了奥氏体长大热模拟试验和第Ⅲ脆性区热拉伸试验。研究结果表明,当冷却速率小于5℃/s时,钛铌微合金钢铸坯表面容易形成粗大的（大于1mm）奥氏体晶粒;随着冷却速率的增大,奥氏体边界析出细小的Ti（C,N）,能有效地钉扎限制奥氏体的长大。在热拉伸试验过程中,当冷却速率为1和5℃/s时,钛铌微合金钢铸坯在800℃热拉伸时断面收缩率仅为29.7%和23.0%,2种冷速下都伴随有70-200nm矩形或不规则形的（Ti,Nb）（C,N）和40-100nm针状的Nb（C,N）析出。铸坯角部振痕谷底处在高温低冷速下形成粗大奥氏体晶粒,并在第Ⅲ脆性区矫直,是导致钛铌微合金钢角部横裂纹敏感性高的主要原因。By Gleeble-3500 thermal simulator, the simulation experiments of austenite grain growth and ductility in the third brittle zone on the surface slab were carried out respectively, which identified the growth regularity of austenite size and hot ductility under different cooling rates. The results show that the austenite ＂blown grains＂（1 mm） with lower cooling rate（5℃/s） are formed easily. The precipitates of fine Ti（C,N） around the austenite boundary could pin and limit the growth of austenite with the increase of cooling rate. In the thermal stretching experiment, reduction of area of Ti-Nb bearing mirco-alloyed steel slab at 800℃ respectively are only 29.7% and 23.0% with cooling rate of 1 and 5℃/s. Both precipitating rectangle or irregular（Ti,Nb）（C,N） precipitates with 70-200 nm size and needlelike Nb（C,N） precipitates with 40-100 nm. The formation of ＂blown grains＂ at the depths of oscillation marks with low cooling rate, and straightening in the third brittle zone are the major causes of high corner transverse crack sensitivity of Ti-Nb micro-alloyed steel slabs.

关 键 词：微合金钢 奥氏体尺寸 热塑性 碳氮化物 冷却速率 

分 类 号：TG142.1[一般工业技术—材料科学与工程]