李德发1，2，王世森1，邢淑清2，熊涛1

( 1．武汉钢铁集团公司研究院，湖北武汉430080; 2．内蒙古科技大学材料与冶金学院，内蒙古包头014010)

关键词: 特厚板; 铌钛微合金化; 析出

中图分类号: TG335． 5; TG142． 1 文献标识码: A

摘要: 通过金相显微镜、TEM 和EDS 等手段，对采用TMCP 工艺研制的Nb-Ti 复合强化Q460 级特厚钢板进行组织性能分析. 结果表明，板厚1 /4 处组织主要为铁素体和少量贝氏体，厚度中心部位有少量珠光体，岛状M/A 组织分布均匀. 铁素体基体上存在大量位错，位错线上的析出相约50 纳米，呈方形或圆形，晶界上析出相约300 nm，呈三角形，析出物均为铌钛的碳氮化物. M/A 组织及细小的析出第二相粒子是贝氏体Q460 特厚钢板的主要强化原因.

Strengthening mechanism of Nb-Ti microalloyed heavy plate on Q460 grade

LI De-fa1，2，WANG Shi-sen1，XING Shu-qing2，XIONG Tao1

( 1． Research and Development Center，Wuhan Iron and Steel ( group) Corp．，Wuhan，430080，China; 2． Materials and Metallurgy School，Inner Mongolia University of Science and Technotogy，Baotou 014010，China)

Key words: heavy plate，Nb-Ti microalloyed，strengthening mechanism

Abstract: The strengthening mechanism of Nb-Ti microalloyed heavy plate produced by means of TMCP was investigated using microscope，EDS and TEM．The plate has the structure consisting of very fine ferrite and a small fraction of bainite with some pearlite and M/A island distribution at the center． There is high density of dislocation existed in the ferrite crystalline grain，with a large number of second-phase particles of small roundness and rectangle． Meanwhile，there are precipitations of TiN，TiC，Nb( CN) scattering in the grain border about 300 nm in thickness． M/A microstructure and the small roundness precipitation of second-phase particles are the main strengthening reasons for Q460 heavy plate．