400MPa级热轧耐火钢筋的研究与开发  

Research and development of 400MPa hot rolled fire resistant steel bar

作　　者：周云 陈焕德 张宇 ZHOU Yun;CHEN Huande;ZHANG Yu(Institute of Research of Iron and Steel,Shagang,Jiangsu Province,Zhangjiagang 215625,China)

机构地区：[1]江苏省(沙钢)钢铁研究院,张家港215625

出　　处：《轧钢》2025年第1期93-100,118,共9页Steel Rolling

基　　金：国家重点研发计划项目(2021YFB3701702);张家港产学研预研资金项目(ZKHBZ2211)。

摘　　要：针对含Mo耐火钢筋的研发,利用高温激光共聚焦显微镜及Gleeble-3800热模拟仪研究了加热温度、终冷温度及冷却速率对Cr-Mo-Nb系耐火钢筋组织及性能的影响,完成了400MPa级热轧耐火钢筋的开发及工业试制。研究结果表明:随着加热温度升高、保温时间延长,耐火钢筋奥氏体晶粒尺寸增大,当加热温度由1150℃提高至1250℃,保温60min后耐火钢筋奥氏体晶粒尺寸由57.5μm提高至142.4μm,当加热温度为1150℃,耐火钢筋空冷组织为铁素体及贝氏体;当冷速由0.5℃/s增大至50℃/s时,耐火钢筋组织中贝氏体和马奥岛含量均明显增多,室温屈服强度由420MPa增大至996MPa;当终冷温度由700℃提高至1100℃,耐火钢筋金相组织均为贝氏体+铁素体,铁素体比例先升高后降低,室温屈服强度在437~457MPa范围内先降低后增大。工业生产时,加热温度1150℃,开轧温度1000~1020℃,轧后弱穿水,上冷床温度900℃,耐火钢筋组织为贝氏体+铁素体+马奥岛,室温屈服强度422~439MPa,室温抗拉强度715~730MPa,强屈比大于1.25,断后伸长率15.2%~16.4%,最大力总伸长率10.1%~11.7%,高温屈服强度301~323MPa。For the development of Mo-containing fire resistant steel bars,the effects of heating temperature,final cooling temperature and cooling rate on the microstructure and properties of Cr-Mo-Nb fire resistant steel bars were studied by confocal laser scanning high-temperature microscope and Gleeble-3800thermal simulator.According to the research results,the 400MPa grade hot rolled fire resistant steel bars were developed and industrial trial produced.The research results show that as the heating temperature increases and the soaking time prolongs,the austenite grain size of fire resistant steel bars increases.When the heating temperature is increased from 1150℃to 1250℃and the soaking time is 60min,the austenite grain size increases from 57.5μm to 142.4μm.When the heating temperature is 1150℃,the microstructure of the air-cooled fire resistant steel bars is ferrite and bainite.When the cooling rate increases from 0.5℃/s to 50℃/s,the content of bainite and M/A islands increased significantly,which corresponds to the yield strength at room temperature from 420MPa to 996MPa.When the final cooling temperature increases from 700℃to 1100℃,the microstructure of the fire resistant steel bars is composed of bainite and ferrite,and the proportion of ferrite increases and then decreases,while the yield strength decreases and then increase between 437-457MPa.In industrial production of the fire resistant steel bars,a combination of heating temperature of 1150℃,starting rolling temperature of 1000-1020℃and final cooling temperature of 900℃after weak water cooling can produce a microstructure of bainite,ferrite and M/A islands,which corresponds to yield strength of 422-439MPa,tensile strength of 715-730MPa,yield ratio higher than 1.25,elongation after fracture of 15.2%-16.4%,total elongation at maximum force of 10.1%-11.7%,and yield strength of 301-323MPa at high temperature.

关 键 词：耐火钢筋 高温金相 加热温度 连续冷却转变 冷却速率 终冷温度 组织性能 

分 类 号：TG335.11[金属学及工艺—金属压力加工]