1000MPa级Nb-Ti微合金化超高强度钢加热制度研究

发布时间：2019-04-08 14:06

【摘要】：采用OM、TEM和EDS分析技术,研究了1000 MPa级Nb-Ti微合金化超高强度钢在不同加热温度下保温不同时间时奥氏体晶粒粗化行为与微合金元素碳氮化物溶解行为。结果表明,铸坯中存在尺寸与形状明显不同的3类析出物:尺寸大于1μm的方形Ti N粒子;尺寸在500 nm以下的球形、椭球形或方形Nb、Ti复合析出物;少量方形或椭球形Ti S或Ti(C,S)析出物。随着温度的升高,原始奥氏体晶粒尺寸呈现出单调增大的趋势,当加热温度超过1200℃时奥氏体晶粒发生快速长大,而析出物数量不断减少、尺寸逐渐增大、Ti/Nb原子比逐渐升高,EDS显示均为Ti、Nb复合析出。随着保温时间的延长,原始奥氏体平均晶粒尺寸呈抛物线规律长大,小尺寸的球形、椭球形的析出物逐渐溶解,大尺寸方形析出物数量逐渐增加且棱角变得模糊。综合考虑加热温度和保温时间对Nb、Ti微合金元素的固溶行为和奥氏体晶粒粗化行为的影响,1000 MPa级Nb-Ti微合金化超高强度钢的加热温度和保温时间分别为1250℃和80 min较合适。
[Abstract]:The coarsening behavior of austenite grain and dissolution behavior of microalloyed carbon nitride of 1000 MPa Nb-Ti microalloyed ultra-high strength steel at different heating temperatures and different time were studied by means of OM,TEM and EDS analysis techniques. The results show that there are three kinds of precipitates which are obviously different in size and shape: square Ti N particles larger than 1 渭 m in size, spherical, ellipsoidal or square Nb,Ti composite precipitates in size less than 500 nm. A small amount of square or ellipsoidal Ti S or Ti (C, S) precipitates. With the increase of temperature, the grain size of original austenite increases monotonously. When the heating temperature exceeds 1200 鈩，

本文编号：2454639