700MPa级别热轧高强钢氧化铁皮结构转变规律  

Structural transformation of oxide scale of 700-MPa grade hot rolled high strength steel

作　　者：曹光明[1] 刘怡私 高欣宇 李光辉[2] 王皓 刘振宇[1] CAO Guang-ming;LIU Yi-si;GAO Xin-yu;LI Guang-hui;WANG Hao;LIU Zhen-yu(The State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,China;VALIN LYsteel Co.,Ltd,Loudi 417000,China)

机构地区：[1]东北大学轧制技术及连轧自动化国家重点实验室,沈阳110819 [2]华菱涟源钢铁有限公司,娄底417000

出　　处：《工程科学学报》2019年第12期1591-1598,共8页Chinese Journal of Engineering

基　　金：国家重点研发计划资助项目（2017YFB0305002）;国家自然科学基金联合基金资助项目（U1660117）;中央高校基本科研业务费资助项目（N180704008）

摘　　要：选取700 L作为试验用典型钢种,利用高温同步热分析仪(TGA)研究了热轧过程中不同卷取温度和冷却速率条件对氧化铁皮结构转变的影响规律.实验结果表明,450~500℃为700 L共析转变的“鼻温”区间,此时共析转变的孕育期最短,容易发生共析转变,生成大量的共析组织(Fe+Fe3O4).相较于其他成分钢种的氧化铁皮共析组织转变规律,700 L中添加的Mn、Nb、Ti元素会使晶粒细化,进而使参与反应的离子的扩散通道增加,并最终使共析转变速率发生一定的延迟,共析“C”曲线整体出现向左偏移.Due to exposure to air during rolling processes,a layer of oxide scale always coats the surface of the hot-rolled steel plates.During the subsequent cooling processes,the FeO in the oxide scale undergoes a eutectic reaction.The formation of a lamellar structure(Fe+Fe3O4)during this reaction is influenced by different cooling methods.The addition of alloying elements,however,also affects the eutectic reaction.The final oxide scale,hence,varieswith different compositions.For 700-MPa grade high strength steels,poor control of iron oxide scale is detrimental to the surface quality;such surface defects as iron oxide scale shedding,surface red rust,pit,are incurred.These defects,however,affect the overall performance of the steel.Consequently,the improvement of the surface quality of hot-rolled steel by controlling the iron oxide scale,without compromising the mechanical properties,has attracted the interest of many researchers.In this paper,the effect of cooling temperature and cooling rate on the structural transformation of tertiary oxide scale during hot-rolling was studied.A sample of 700 L steel grade was used.The study was carried out by the thermogravimetric analysis(TGA).The results show a"nose temperature"range of 450‒500℃for the 700 L eutectoid transformation.The FeO shows the shortest incubation period of eutectoid transformation,hence,is prone to eutectoid transformation,forminga large number of eutectoid phase(Fe+Fe3O4).Addition of alloying elements such as manganese(Mg),niobium(Nb),and titanium(Ti)to the 700 L steel lead to grain refinement in the steel.It also increases the amount of diffusion channel of ions that participate in the eutectoid phase transformation.Consequently,the eutectoid transformation is delayed,and the eutectoid“C”curve shifts to the left.This is comparableto the eutectoid transformation rule of oxide scale on the surface of other steel grades.

关 键 词：高强钢 氧化铁皮 结构转变 共析“C”曲线 MN元素 

分 类 号：TG335.1[金属学及工艺—金属压力加工]