热循环峰值温度对G115钢管热影响区微观组织与性能的影响  

Effect of peak temperature of thermal cycling on microstructure and properties of heat affected zone of G115 steel pipe

作　　者：陈千 陈正宗[1] 刘正东[1] 蔡文河 姜海峰 包汉生[1] 何西扣[1] Chen Qian;Chen Zhengzong;Liu Zhengdong;Cai Wenhe;Jiang Haifeng;Bao Hansheng;He Xikou(Research Institute of Special Steels,Center Iron and Steel Research Institute Co.,Ltd.,Beijing 100081,China;China Datang Corporation Science and Technology Research Institute Co.,Ltd.,Beijing 200940,China;Datang Yuncheng Power Generation Co.,Ltd.,Yuncheng Shandong 274700,China)

机构地区：[1]钢铁研究总院有限公司特殊钢研究院,北京100081 [2]中国大唐集团科学技术研究院有限公司,北京200940 [3]大唐郓城发电有限公司,山东郓城274700

出　　处：《金属热处理》2025年第2期114-120,共7页Heat Treatment of Metals

基　　金：国家重点研发计划(2021YFB3704104)。

摘　　要：通过Gleeble-1500D热模拟试验机对G115钢管热影响区开展分区热模拟,结合OM、SEM、EBSD、TEM及显微硬度计等对热影响区亚区的显微组织结构及硬度进行分析。结果表明,G115钢管焊接热影响区主要分为粗大等轴晶的粗晶区(CGHAZ)、破碎细小晶粒包围着大晶粒的精细混晶结构的细晶区(FGHAZ)、与母材差异不大为回火马氏体组织的临界区(ICHAZ);完全相变组织(CGHAZ、FGHAZ)的几何位错密度(24.1×10^(14)、24.5×10^(14)m^(-2))约是未完全相变组织(ICHAZ)(13.6×10^(14)、11.8×10^(14)m^(-2))的两倍,即ICHAZ与FGHAZ界面处存在较高的应力应变梯度;FGHAZ组织内仅少量存在M_(23)C_(6)和Laves相,在更高温度下可完全溶解;CGHAZ内仍少量分布MX相,富Cu相以球状仅于ICHAZ晶内析出。热模拟后组织-硬度与热循环峰值温度呈正相关,其中CGHAZ显微硬度为437.55 HV0.2,FGHAZ硬度为421.85 HV0.2,临近母材处ICHAZ的硬度约为375 HV0.2。Heat affected zone(HAZ)of the G115 steel pipe was simulated by Gleeble-1500D thermal simulation machine,and the microstructure and hardness of the subregions of heat affected zone were analyzed by means of OM,SEM,EBSD,TEM and microhardness tester.The results indicate that the welded heat affected zone of G115 steel pipe is mainly divided into the coarse grain heat affected zone(CGHAZ)with coarse equiaxed grains,the fine grain heat affected zone(FGHAZ)with a fine mixed grain structure of large grains surrounded by crushed fine grains,and the intercritical heat affected zone(ICHAZ)with tempered martensite,which shows a little difference from the base metal.The geometric dislocation density of the fully phase-transformed microstructure(CGHAZ,FGHAZ)(24.1×10^(14),24.5×10^(14)m^(-2))is approximately twice that of the incompletely phase-transformed microstructure(ICHAZ)(13.6×10^(14),11.8×10^(14)m^(-2)),meaning that there is a significant stress-strain gradient at the interface between ICHAZ and FGHAZ.Only a small number of M_(23)C_(6)and Laves phases are present within the FGHAZ,which can completely dissolve at higher temperatures.The complete dissolution temperature of the MX phase is higher,and it is still distributed in a small number in the CGHAZ.The Cu-rich phase only precipitates spherically within the grains at the ICHAZ.After the thermal simulation,the hardness and microstructure are positively correlated with the thermal cycling peak temperature.The microhardness of the CGHAZ,FGHAZ and ICHAZ near the base metal is 437.55,421.85 and about 375 HV0.2,respectively.

关 键 词：G115钢管 焊接热循环 微观组织 硬度 

分 类 号：TG142.1[一般工业技术—材料科学与工程]