Ni含量及控冷工艺对力学性能的影响.DOC

轧后冷却工艺对海洋平台用钢组织性能的影响 狄国标1，周砚磊2，姜中行1，刘振宇2， （1.首钢技术研究院，北京 100041； 2.东北大学轧制技术及连轧自动化国家重点实验室，辽宁 沈阳110004） 摘 要：轧后采用空冷、加速冷却和两段式（前段超快冷+后段加速冷却，简称超快冷）三种冷却模式进行控制冷却，研究了冷却工艺对海洋平台用钢组织性能的影响。结果表明，空冷工艺所得实验钢的组织为多边形铁素体和马氏体，铁素体晶粒内位错密度较低，析出相数量较少，尺寸粗大；加速冷却所得实验钢的显微组织由多边形铁素体、针状铁素体和细小弥散的M/A岛组成，铁素体晶粒较空冷工艺明显细化，位错密度提高，析出物细小弥散；两段式所得实验钢的相变组织主要为针状铁素体，板条明显细化，位错密度进一步提高，析出物细小而数量降低。三种冷却工艺中，空冷工艺所得实验钢的屈强比最低，塑性最好；加速冷却工艺所得实验钢的低温韧性最佳；而采用两段式冷却工艺所得实验钢抗拉强度最高。 关键词：低温韧性冷却工艺屈强比M/A岛 中图分类号：TG142.1文献标志码：A Effect of cooling mode on microstructure and mechanical properties of offshore platform steel DI Guo-biao1, ZHOU Yan-lei2, JANG Zhong-hang1, LIU Zhen-yu2 , MA Qing-shen1 (1.Shougang Research institute of Technology, Beijing 100041,China;2.The State Key Laboratory of Rolling and Automation of Northeastern University, Shenyang 110004 ,China) Abstract: In order to investigate the effect of cooling routes on the microstructure and mechanical properties of offshore platform steel, three types of cooling mode which includes air cooling, accelerated cooling (ACC), and two-stage cooling(ultra fast cooling (UFC) + ACC) was applied after hot rolling. It has been shown that polygonal ferrite and martensite were obtained through air cooling process. Dislocation density in polygonal ferrite is relative low and precipitates are large, sparsely distributed. Accelerated cooling mode has resulted in the microstructure which consists of polygonal ferrite, acicular ferrite and fine dispersed M/A island. Compared with air cooling mode, the ferrite grain is refined with increased dislocation density and fine dispersed precipitates. The microstructure attained from two-stage cooling mode is mainly acicular ferrite with markedly refined ferrite lath and further increased dislocation density and less fine dispersed precipitates.Among the three cooling modes, the lowest yield ratio and highest plasticity have been achieved through air cooling. The accelerated cooling and two-stage cooling has resulted in the optimal low-temperat