不同冷却方式下X80M管线钢的组织演变  

Microstructure evolution of X80M pipeline steel under different cooling methods

作　　者：蔡绪明 李艳梅[2] 李中平[3] 周文浩[3] 陈炼 熊祥江[3] CAI Xuming;LI Yanmei;LI Zhongping;ZHOU Wenhao;CHEN Lian;XIONG Xiangjiang(Shashi Steel Works,Sinopec Oilfield Equipment Corporation,Jingzhou 434001,China;Northeastern University,Shenyang 110819,China;Hunan Valin Xiangtan Iron and Steel Co.,Ltd.,Xiangtan 411101,China)

机构地区：[1]中石化石油机械股份有限公司沙市钢管分公司,湖北荆州434001 [2]东北大学,辽宁沈阳110819 [3]湖南华菱湘潭钢铁有限公司,湖南湘潭411101

出　　处：《轧钢》2023年第1期41-45,共5页Steel Rolling

摘　　要：针对当前开发高强韧性、低屈强比管线钢的需求,利用光学显微镜和透射电镜,研究了4种不同冷却方式下X80M管线钢的组织性能演变。结果表明:轧后空冷钢板的屈强比较高,金相组织主要为PF+P,没有明显的亚结构,位错密度低,强度低,均匀伸长率好,但落锤性能差;轧后钢板弛豫至Ar3温度以下,水冷前会先析出一部分PF,快速冷却过程中富碳奥氏体在更低温下会发生贝氏体转变,随着冷却速率的增大,组织形貌由块状演化为条片状贝氏体,由PF+B的双相组织构成,存在较高密度的位错,具有较好的均匀伸长率与硬化指数,该工艺适合抗大变形管线钢的生产;轧后钢板直接快速冷却至Ms温度以下,钢板强度高韧性好,但均匀伸长率与硬化指数下降,金相组织为典型AF+MA,该工艺适合常规高钢级管线钢的生产。Aiming at the current demand of developing pipeline steel with high strength, toughness and low yield ratio, the microstructure and property evolution of X80M pipeline steel under four different cooling methods was studied by using optical microscope and transmission electron microscope. The results show that the yield ratio of the air cooled plate after rolling is high, the microstructure is mainly PF+P, there is no obvious substructure, the dislocation density is low, the strength is low, the uniform elongation is good, but the DWTT property is poor. The rolled plate relaxed to the temperature below Ar3and a part of PF was precipitated before water cooling. During rapid cooling, carbon-rich austenite would undergo bainite transformation at a lower temperature. With the increase of cooling rate, the microstructure evolved from block to strip bainite, which was composed of PF+B dual-phase microstructure, with high density dislocation, good uniform elongation and hardening index. This process is suitable for the production of pipeline steel with large deformation resistance. The rolled plate directly and rapidly cooled to the temperature below Mshad high strength and good toughness, but the uniform elongation and hardening index were decreased, and the metallographic structure was typical AF+MA. This process is suitable for the production of conventional high grade pipeline steel.

关 键 词：冷却方式 X80M管线钢 低屈强比 组织 均匀伸长率 

分 类 号：TE973[石油与天然气工程—石油机械设备] TG142.1[一般工业技术—材料科学与工程]