变形和冷却工艺对含Ti-Nb高强汽车用钢组织性能的影响  

Effect of deformation and cooling process on microstructure and mechanical properties of Ti-Nb microalloyed high strength automotive steel

作　　者：刘怡私 梁亮[1] 宫成 姜珊 曹光明[2] 周晓光[2] LIU Yisi;LIANG Liang;GONG Cheng;JIANG Shan;CAO Guangming;ZHOU Xiaoguang(Centre for Product and Technology,Hunan Valin Lianyuan Iron and Steel Co.,Ltd.,Loudi 417009,China;State Key Laboratory of Rolling and Automation,Northeasten University,Shenyang 110819,China)

机构地区：[1]湖南华菱涟源钢铁有限公司技术中心,湖南娄底417009 [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

出　　处：《轧钢》2023年第2期39-45,共7页Steel Rolling

基　　金：国家重点研发计划项目(2022YFB3304800);辽宁省科技专项项目(2022 JH25/10200001);中国博士后科学基金项目(2022T150205)。

摘　　要：为进一步降低成本和提高生产效率,通过热模拟实验研究了奥氏体化温度、变形温度、冷却速率和卷取温度对抗拉强度650 MPa级Ti-Nb微合金化汽车用钢组织和性能的影响规律,并进行了工业试制。结果表明:随着板坯加热温度的升高,实验钢中的析出物回溶于奥氏体中,使得奥氏体晶粒尺寸逐渐增大,综合考虑奥氏体晶粒尺寸大小和均匀程度,实验钢的最优奥氏体化温度为1220℃;随着变形温度的升高,实验钢中的铁素体体积分数逐渐减少,晶粒逐渐粗化,实验钢的硬度变化是细晶强化和相变强化综合作用的结果;随着冷却速率的增加,实验钢中铁素体含量逐渐降低且晶粒逐渐细化,实验钢硬度增加;随着卷取温度的升高,实验钢的硬度逐渐降低,在本实验条件下最优的卷取温度为650℃。基于热模拟研究结果,在工业现场成功制备出抗拉强度650 MPa级高强汽车用钢,其组织为铁素体和少量的贝氏体;其屈服强度、抗拉强度、伸长率分别为593 MPa,676 MPa和24.2%,满足EN 10149.2—1996标准的要求。In order to further reduce costs and improve production efficiency,the effects of austenitizing temperature,deformation temperature,cooling rate and coiling temperature on the microstructure and mechanical properties of Ti-Nb microalloying automotive steel with tensile strength of 650 MPa were studied by thermal simulation experiments,and industrial trial production was carried out.The results show that with the increase of slab heating temperature,the precipitates in the experimental steel dissolve back into the austenite,making the austenite grain size gradually increase.Considering the size and uniformity of the austenite grain,the optimum austenitizing temperature of the experimental steel is 1220℃.With the increase of deformation temperature,the volume fraction of ferrite in the experimental steel gradually decreases,and the grain size gradually coarsens.The variation of the hardness for the experimental steel is the result of the combination of fine grain strengthening and phase transformation strengthening.With the increase of cooling rate,the ferrite volume fraction in the experimental steel decreases gradually and the grain size is gradually refined,and the hardness of the experimental steel increases.With the increase of coiling temperature,the hardness of the experimental steel decreases gradually,and the optimal coiling temperature is 650℃under this experimental condition.Based on the results of thermal simulation,650 MPa high strength automotive steel with microstructure of ferrite and a small amount of bainite was successfully trial-produced in the industrial site.The yield strength,tensile strength and elongation of trial steel are 593 MPa,676 MPa and 24.2%,respectively,meeting the requirements of EN 10149.2—1996.

关 键 词：高强汽车用钢 Ti-Nb微合金化 奥氏体化 工艺参数 组织 力学性能 

分 类 号：TG142.1[一般工业技术—材料科学与工程] U465.11[金属学及工艺—金属材料]