一种高强度钢的CCT曲线的测定与分析  

Determination and analysis of CCT curve of a high strength steel

作　　者：王幸[1] 李红英[1] 汤伟[2] 罗登[2] 刘丹[2] 李阳华[3] 彭宁琦[2] 熊祥江[2] WANG Xing;LI Hongying;TANG Wei;LUO Deng;LIU Dan;LI Yanghua;PENG Ningqi;XIONG Xiangjiang(School of Materials Science and Engineering,Central South University,Changsha 410083,China;Xiangtan Iron&Steel Co.Ltd.of Hunan Valin,Xiangtan 411101,China;Hengyang Valin Steel Tube Co.Ltd.,Hengyang 421001,China)

机构地区：[1]中南大学材料科学与工程学院,湖南长沙410083 [2]湖南华菱湘潭钢铁有限公司,湖南湘潭411101 [3]衡阳华菱钢管有限公司,湖南衡阳421001

出　　处：《中南大学学报（自然科学版）》2021年第4期1090-1098,共9页Journal of Central South University:Science and Technology

基　　金：长株潭国家自主创新示范区专项(2018XK2301)。

摘　　要：通过Gleeble-3500热模拟机测定热轧态钢以不同速度连续冷却到室温的膨胀曲线,结合微观组织观察和硬度测试,绘制出一种高强度钢的CCT曲线,并分析不同冷却速度对组织演变及硬度的影响。研究结果表明:当冷却速度小于0.2℃/s时,主要发生铁素体转变和贝氏体转变,转变产物为多边形铁素体+上贝氏体+粒状贝氏体的混合组织;当冷却速度处于0.5~1.0℃/s范围时,主要发生贝氏体转变,对应0.5℃/s冷却速度的转变产物以上贝氏体为主,对应1.0℃/s冷却速度的转变产物以下贝氏体为主;当冷却速度介于1.0~5.0℃/s之间时,发生贝氏体+马氏体转变,转变产物为下贝氏体+板条马氏体的混合组织;当冷却速度大于等于5.0℃/s时,主要发生马氏体转变,微观组织以板条马氏体为主。当冷却速度小于5.0℃/s时,硬度随冷却速度增大显著增加;当冷却速度大于25.0℃/s时,硬度变化不大。The dilatometric curves of hot-rolled steel continuously cooled to room temperature at different cooling rates were measured by Gleeble-3500 thermal simulator. Combined with microstructure observation and hardness test, the CCT curve of a high strength steel was plotted, and the influence of different cooling rates on microstructure evolution and hardness was analyzed. The research results show that when the cooling rate is less than 0.2 ℃/s, ferrite transformation and bainite transformation mainly occur, and the transformation product is a mixed structure of pre-eutectoid polygonal ferrite+upper bainite+granular bainite;when the cooling rate is in the range of 0.5-1.0 ° C/s, bainite transformation occurs mainly. The transformation product corresponding to the cooling rate of 0.5 ℃/s is mainly upper bainite, and the transformation product corresponding to the cooling rate of 1.0 ℃/s is lower bainite;when the cooling rate is 1.0–5.0 ℃/s, bainite+martensite transformation occurs, and the transformation product is a mixed structure of lower bainite+lath martensite;when the cooling rate is greater than or equal to 5.0℃/s, martensite transformation mainly occurs, and the microstructure is mainly lath martensite.When the cooling rate is less than 5.0 ℃/s, the hardness increases significantly with the increase of cooling rate.When the cooling rate is greater than 25.0 ℃/s, the hardness changes little.

关 键 词：高强度钢 CCT曲线 显微组织 热模拟 连续冷却 

分 类 号：TG142.1[一般工业技术—材料科学与工程]