轧后冷却工艺对铌钛微合金化低碳贝氏体钢组织性能的影响  

Effect of Cooling Process After Rolling on Microstructure and Mechanical Property of Nb-Ti Microalloyed Low-Carbon Bainite Steel

作　　者：李德发[1,2] 王世森[2] 熊玉彰[2] 邢淑清[1] 熊涛[2] 余宏伟[2] 

机构地区：[1]内蒙古科技大学材料与冶金学院,内蒙古包头014010 [2]武汉钢铁(集团)公司研究院,湖北武汉430080

出　　处：《钢铁》2013年第3期71-75,共5页Iron and Steel

基　　金：内蒙古自然科学基金资助项目(2009MS0811);内蒙古科技大学材料加工过程模拟创新团队基金项目(52303001)

摘　　要：利用金相显微镜、SEM、TEM方法研究了轧后冷却制度对铌钛微合金化低碳贝氏体钢微观组织结构、第二相析出及力学性能的影响。结果表明:轧后空冷(弛豫)至一定温度后加速冷却获得铁素体/贝氏体双相组织;随轧后空冷终止温度降低,铁素体含量增加,晶粒尺寸越大,第二相析出尺寸也有长大趋势,贝氏体形态发生改变,贝氏体板条边界和取向越不明显,位错密度降低,M/A形态也发生一定变化;力学性能表现为强度降低,屈强比和韧塑性得到改善。当轧后空冷终止温度在725～740℃,然后以15℃/s的冷却速度冷却至440℃,可以获得良好的综合力学性能,性能满足标准GB/T 1591中Q690要求。The effects of cooling process after rolling on microstructure, precipitated phase and mechanical properties of low carbon bainite steel were investigated by method of SEM and TEM. The results show that ferrite and bainite dual phases can be obtained with air-cooling and accelerated cooling process after hot-rolled. The percentage of ferrite phase increases with the end of air-cooling temperature reduced, the size of ferrite and precipitated phase is lar- ger, the lath of bainite is sharper and the edge is clearer. The shape of M/A constituent is film-like and changes with temperature. When temperature of completion in air-cooling are between 725 ℃ and 740℃ then it is cooled to 440 ℃ with cooling rate of 15 ℃/s, the comprehensive mechanical properties are excellent and can reach the require ments of Q690 of GB/T1591.

关 键 词：铌钛微合金钢 低碳贝氏体 冷却制度 组织 性能 

分 类 号：TG335[金属学及工艺—金属压力加工]