中碳微合金化钢高温延塑性的研究

来源期刊：钢铁2010年第6期

论文作者：龚雅林 张炯明 甄新刚 陈少东 姚永宽 王道远

文章页码：67 - 73

关键词：微合金化钢； 连铸； 高温延塑性； 表面微裂纹

Key words：micro-alloying steel； continuous casting； hot ductility； surface micro-crack

摘    要：借助Gleeble1500热模拟试验机测试了含Nb和含Nb、Ti两种中碳微合金化钢的高温力学行为,分析了析出物、相变、动态再结晶对微合金化钢高温延塑性的影响。结果表明:试验钢种无第Ⅱ脆性区出现;含Nb钢第Ⅲ脆性区的温度范围为950~700℃,含Nb、Ti钢第Ⅲ脆性区的温度范围为900~725℃;微合金化元素Ti的加入可以细化奥氏体晶粒使含Nb微合金化钢高温塑性槽变窄、变浅;析出物沿晶界多而细小的析出和γ^→α相变是第Ⅲ脆性区微合金化钢高温延塑性变差的主要原因。实际生产中通过优化二冷区水量,采用弱冷,可以有效降低微合金化钢表面微裂纹的发生率。

Abstract: High temperature mechanical behaviors of Nb and Nb,Ti containing steel were tested by Gleeble1500 thermal simulation testing machine.Meanwhile,influences of precipitate,phase change and dynamic recrystallization on hot ductility of the micro-alloy steel were also analyzed.The results demonstrate that the brittle zone Ⅱ does not exist.The temperature range of brittle zone Ⅲ is about 950-700 ℃ in Nb containing steel and 900-725 ℃ in Nb,Ti containing steel.The addition of micro-alloying element Ti can refine austenite grains thus the hot ductility trough of Nb containing steel becomes narrow and shallow.Both precipitations along the grain boundaries and during γ^→α phase transformation are main factors which lead to a decrease on hot ductility of Nb and Nb,Ti containing steel.In the practice process the incidence of surface micro-cracks in micro-alloying steel can be reduced dramatically by decreasing specific water rate in secondary cooling zone.