超快冷工艺对DP780热轧带钢组织性能的影响  

Effect of ultra-fast cooling process on microstructure and properties of DP780 hot rolled strip

作　　者：孙丽荣 丁敬国[2] 万佳峰 蔡明晖 SUN Lirong;DING Jingguo;WAN Jiafeng;CAI Minghui(Shandong Iron and Steel Group Rizhao Co.,Ltd.,Rizhao 276800,China;State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,China;School of Material Science and Engineering,Northeastern University,Shenyang 110819,China)

机构地区：[1]山东钢铁集团日照有限公司热轧厂,山东日照276800 [2]东北大学轧制技术及连轧自动化国家重点实验室,辽宁沈阳110819 [3]东北大学材料科学与工程学院,辽宁沈阳110819

出　　处：《轧钢》2024年第4期51-58,65,共9页Steel Rolling

基　　金：国家重点研发计划项目(2022YFB3304800);国家自然科学基金项目(U21A20475)。

摘　　要：针对低成本、高性能DP780热轧带钢的开发,对其化学成分进行了优化设计,减少了昂贵合金元素Cr、Mo、V等的添加,优化了C、Si、Mn含量设计,设计化学成分为:w(C)=0.105%、w(Si)=1.15%、w(Mn)=1.7%、w(Ti)=0.01%;结合前置式超快冷+层流冷却+后置超快冷组合的一体化超快冷系统,建立了基于极限学习机的超快冷换热系数机器学习模型,有效提高了前置式超快冷出口温度和卷取温度的控制精度。基于此,研究了前段超快冷出口温度和卷取温度对DP780热轧带钢微观组织演变和力学性能的影响规律。研究结果表明:当卷取温度设定为190℃,DP780热轧带钢的微观组织为铁素体和马氏体,随着前段超快冷出口温度的降低,马氏体体积分数逐渐减少,铁素体体积分数逐渐增加;当前段超快冷出口温度设定为610℃,卷取温度为230℃时,热轧带钢的微观组织主要为铁素体、马氏体和少量的贝氏体,但随着卷取温度的降低,组织中的贝氏体逐渐消失,马氏体体积分数减少,铁素体体积分数增大。采用热轧及超快冷一体化调控工艺,获得了低成本、高性能的DP780热轧带钢,屈服强度为641 MPa、抗拉强度为1068 MPa、断裂伸长率为11.5%、强塑积达12282MPa·%。Aiming at the development of low-cost,high-performance DP780 hot rolled strip,the chemical composition of the optimized design is carried out to reduce the addition of expensive alloying elements Cr,Mo,V,etc.,and the content design of C,Si,Mn is optimized.The designed chemical composition is as follows:w(C)=0.105%,w(Si)=1.15%,w(Mn)=1.7%,w(Ti)=0.01%.Combined with the integrated ultra-fast cooling system of front ultra-fast cooling+laminar cooling+rear ultra-fast cooling,a machine learning model of ultra-fast cooling heat transfer coefficient based on extreme learning machine was established,which effectively improved the control accuracy of the outlet temperature of front ultra-fast cooling and coiling temperature.Based on this,the effects of the front ultra-fast cooling outlet temperature and coiling temperature on the microstructure evolution and mechanical properties of DP780 hot rolled strip was investigated.The results show that the microstructure of DP780 hot rolled strip is ferrite and martensite when the coiling temperature is set at 190℃.The volume fraction of martensite decreases and the volume fraction of ferrite increases with the decrease of the front ultra-fast cooling outlet temperature.The microstructure of hot rolled strip is mainly ferrite,martensite and a small amount of bainite when the front ultra-fast cooling outlet temperature is set at 610℃and the coiling temperature is 230℃.However,with the decrease of coiling temperature,the bainite in the microstructure gradually disappears,the volume fraction of martensite decreases,and the volume fraction of ferrite increases.The DP780 hot rolled strip with low cost and high performance was obtained by the integrated control process of hot rolling and ultra-fast cooling,with yield strength of 641 MPa,tensile strength of 1068 MPa,elongation at break of 11.5%and strong plastic volume of 12282 MPa·%.

关 键 词：DP780热轧带钢 超快冷工艺 前段超快冷出口温度 卷取温度 机器学习 组织性能 低成本 

分 类 号：TG142.1[一般工业技术—材料科学与工程] TG335.11[金属学及工艺—金属材料]