摘要
使用Formaster-FⅡ热膨胀仪,结合光学显微镜(OM)、扫描电镜(SEM)和维氏硬度测试,绘制了某船用高强球扁钢的连续冷却转变(CCT)曲线,并对其升温过程中的奥氏体转变进行动力学分析。结果表明,试验钢的Ac_(1)=672℃、Ac_(3)=793℃。在0.06~38.2℃/s冷速范围内,不发生珠光体转变。冷速为0.06~0.3℃/s时,发生贝氏体转变,且随冷速提高,贝氏体含量减少;冷却速度为0.8~3.8℃/s时,发生马氏体-贝氏体混合相变,随着冷速提高,马氏体含量增加;冷却速度为7.6~38.2℃/s时,发生马氏体相变。随着冷却速度的升高,试验钢硬度先快速升高,冷速达到7.6℃/s后硬度增加减缓,冷速为38.2℃/s时,硬度达最大值359 HV5。利用热膨胀曲线和杠杆定律得到升温过程试验钢的奥氏体转变动力学方程,表明其奥氏体转变为三维方式生长。
Continuous cooling transformation(CCT)curve of a high strength bulb flat ship steel was plotted by using Formaster-FⅡthermal dilatometer combined with optical microscope(OM),scanning electron microscope(SEM),and Vickers hardness test,and austenite transformation kinetic analysis during the heating process was conducted.The results show that the Ac_(1) and Ac_(3) of the tested steel are 672℃and 793℃,respectively.Within the cooling rate range of 0.06-38.2℃/s,no pearlite transformation is observed.When the cooling rate is 0.06-0.3℃/s,bainite transformation occurs,and the bainite volume fraction decreases with the increase of cooling rate.When the cooling rate ranges from 0.8℃/s to 3.8℃/s,mixed martensite-bainite phase transformation occurs,and the volume fraction of martensite increases with the increase of cooling rate.Martensitic transformation occurs within the cooling rate range of 7.6℃/s to 38.2℃/s.With the increase of the cooling rate,the hardness of the tested steel first increases rapidly.After the cooling rate reaches 7.6℃/s,the hardness increases slowly,and reaches the maximum value of 359 HV5 at the cooling rate of 38.2℃/s.The kinetics equation of austenite transformation is derived from the thermal dilatometric curve combined with the lever rule,revealing that the austenite transformation during the heating process follows a three-dimensional growth mechanism.
作者
祁震
梁丰瑞
罗小兵
柴锋
葛启录
展之德
宋成民
罗坤杰
Qi Zhen;Liang Fengrui;Luo Xiaobing;Chai Feng;Ge Qilu;Zhan Zhide;Song Chengmin;Luo Kunjie(Research Institute of Engineering Steels,Central Iron and Steel Research Institute Co.,Ltd.,Beijing 100081,China;Suzhou Nuclear Power Research Institute Co.,Ltd.,Suzhou Jiangsu 215004,China)
出处
《金属热处理》
北大核心
2025年第8期1-7,共7页
Heat Treatment of Metals
基金
钢铁研究总院有限公司自主投入研发专项基金(事24G60740Z)。
关键词
球扁钢
CCT曲线
组织转变
相变动力学
bulb flat steel
CCT curve
microstructure transformation
phase transformation kinetics
作者简介
祁震(1995-),男,博士研究生,主要研究方向为船舶及海工用钢材料开发,E-mail:1744616867@qq.com;通信作者:罗坤杰,正高级工程师,E-mail:15544838783@163.com。
