摘要
针对Q500MEZ35厚板在线冷却能力不足难以淬透的问题,对其厚度40 mm钢板进行了试制开发。在冶炼过程中,通过控制S元素质量分数不大于0.002%、加入Ca线和稀土元素Ce等措施,来减小夹杂物尺寸,以提高钢板Z向抗层状撕裂性能。采用低温大形变的精轧工艺,使其析出更多、更细小的(Ti, Nb, V)(C,N)第二相粒子,为后续铁素体相变提供更多的形核位置。通过不同的终冷温度(580~350℃)试验发现,随着终冷温度的降低,C原子长程扩散能力减弱,残余奥氏体的稳定性降低,从而使M/A岛的尺寸减小。同时,铁素体晶粒以切变的方式在位错处形核,并受C的扩散限制而长大,最终形成细小的板条束针状铁素体。当终冷温度在350℃时,钢板主要组织为细小的粒状贝氏体和针状铁素体,冲击性能最好。
Aiming at the problem that Q500MEZ35 heavy plate is difficult to quench through due to the insufficient on-line cooling capacity,the 40 mm thickness plate was developed for trial production.In the process of steel smelting,the inclusion size can be reduced by controlling the mass fraction of S element less than 0.002%,adding Ca line and rare earth element Ce,etc.,so as to improve the Z-direction resistance to laminar-tear of plate.More and smaller(Ti,Nb,V)(C,N)second phase particles were precipitated by the finishing rolling process with low temperature and large deformation,which provided more nucleation sites for the subsequent ferritic transformation.Through different final cooling temperatures(580-350 C)tests,it is found that with the decrease of final cooling temperature,the long-range diffusion ability of C atom is weakened,the stability of residual austenite is reduced,and the size of M/A island is reduced.At the same time,the ferrite grains nucleate in shear mode and grow up due to the limitation of C diffusion,and finally form fine lath acicular ferrite.When the final cooling temperature is 35o C,the main microstructure of the plate is fine granular bainite and acicular ferrite,and the impact property is the best.
作者
郑海明
刘庆波
李忠波
唐郑磊
于飒
庞百鸣
ZHENG Haiming;LIU Qingbo;LI Zhongbo;TANG Zhenglei;YU Sa;PANG Baiming(Steel Research Institute,Nanyang Hanye Special Iron and Steel Co.,Ltd.,Nanyang 474500,China;Metallurgical and Ecological Engineering School,University of Science and Technology Beijing,Beijing 100083,China)
出处
《轧钢》
北大核心
2024年第3期133-138,共6页
Steel Rolling
关键词
Q500MEZ35厚板
夹杂物
低温大形变
终冷温度
针状铁素体
Q500MEZ35 heavy plate
inclusions
low temperature and large deformation
final cooling temperature
acicular ferrite
