700MPa级高强钢焊接热模拟粗晶区组织转变规律  

Microstructure Evolution of CG-HAZ by Thermal Simulation for 700MPa Grade High Strength Steel

作　　者：刘旭辉[1] 欧玲 肖爱达[1] 曾威民 LIU Xuhuil;OU Ling;Xiao Aidal;ZENG Weiminl(Lianyuan Iron and steel Co.Ltd.,Loudi 417009,China;School of Metallurgical Engineering,Hunan University of Technology,Zhuzhou 412000,China)

机构地区：[1]湖南华菱涟源钢铁有限公司,湖南娄底417009 [2]湖南工业大学冶金与材料工程学院,湖南株洲412000

出　　处：《金属材料与冶金工程》2018年第5期46-49,55,共5页Metal Materials and Metallurgy Engineering

摘　　要：采用热模拟技术研究了700 MPa级高强钢不同冷却速度条件下热影响区粗晶区(CGHAZ)的组织和性能,获得热影响区连续冷却转变曲线。得到的结果为:t8/5在4~6 s时,硬度值变化不大, CGHAZ组织为板条马氏体。当冷却速度在10~60 s时,随着冷却速度的降低, CGHAZ显微硬度逐渐降低,组织为马氏体和粒状贝氏体。t8/5增加至150 s后,组织基本为粒状贝氏体组织。当t8/5在30 s时,粗晶区显微硬度为269HV1,与基材(266.5HV1)相当。焊接时应控制热输入,使t8/5小于30 s,以保证焊接接头的强度。CEN为0.488%,冷裂纹敏感指数Pcm为0.256%,说明试验钢具有一定的淬硬和冷裂倾向。The microstructure and property of the coarse grained heat affected zone （CGHAZ） of 700 MPa grade steel was studied by using thermal simulation technology, and the continuous cooling transformation curve of the heat affected zone （SH-CCT diagram） was acquired. The results show that, the microstructure of the CGHAZ consists of lath martensite and the hardness values change little when t8/5 is 4-6 s. When t8/5 is 10-60 s, with the increase of t8/5 , the microhardness of CGHAZ gradually reduces. When t8/5 is over 150 s, the microstructure is basically granular bainite. When t8/5 is 30 s, the microhardness of CGHAZ （269HV1） equals to the base metal （266.5HV1） . So the heat input should be controlled to ensure that t8/5 is less than 30 s. The carbon equivalent and cold cracking susceptibity coefficient of this steel is 0.488% and 0.256%, which show that the test steel is apt to hardening and cold cracking.

关 键 词：焊接热模拟 热影响区粗晶区 SH—CCT图 显微组织 硬度 

分 类 号：TG457.11[金属学及工艺—焊接]