V-N微合金化X80抗大变形管线钢的组织与力学性能

通过热模拟试验机研究了V-N微合金钢过冷奥氏体动态连续冷却相变行为，设计了V-N微合金化X80抗大变形管线钢的轧制与冷却工艺参数并分析了组织和力学性能的关系.结果表明，动态CCT曲线出现高温转变区和中温转变区分离的现象，转变温度范围分别是637~728℃和441~601℃，当冷速为10~20℃/s时，形成针状铁素体为主的组织.V-N微合金化管线钢组织以多边形铁素体和针状铁素体为主，屈服强度、抗拉强度、均匀延伸率和-20℃夏比冲击功分别为603MPa，724MPa，11.1%和214J，满足API Spec 5L对X80管线钢的力学性能要求，同时具有好的强塑性匹配.

Microstructure and Mechanical Properties of V-N Microalloyed X80 High Deformability Pipeline Steel

The dynamic continuous cooling transformation behavior of undercooled austenite in a V-N microalloyed steel was studied by means of thermal simulation test machine. Furthermore， the rolling and cooling process parameters of V-N microalloyed X80 high deformability pipeline steel were designed and the relationship between microstructure and mechanical properties was analyzed. The dynamic CCT curve shows a separation of high temperature transformation region and intermediate temperature transformation region， and the transformation ranges are 637~728℃ and 441~601℃， respectively. When the cooling rate is in the range of 10~20℃/s， the microstructure mainly consists of acicular ferrite. The microstructure of V-N microalloyed pipeline steel is dominated bypolygonal ferrite and acicular ferrite. Yield strength， tensile strength， uniform elongation and -20℃ Charpy impact energy are 603MPa， 724MPa， 11.1% and 214J， respectively. These meet the requirements of X80 pipeline steels according to the API Spec 5L specification that the produced pipeline steel should have a good combination of strength and ductility.