电力火灾场景Q355B钢力学性能及微观组织分析  

Mechanical properties and microstructure analysis of Q355Bsteel in power fire scenario

作　　者：侯东 聂京凯 刘晓圣 陈国宏 姬军 韩钰 HOU Dong;NIE Jingkai;LIU Xiaosheng;CHEN Guohong;JI Jun;HAN Yu(State Key Laboratory of Advanced Power Transmission Technology,State Grid Smart Grid Research Institute Co.,Ltd.,Beijing 102209,China;Department of Electrical Engineering New Materials,State Grid Smart Grid Research Institute Co.,Ltd.,Beijing 102209,China;State Grid Anhui Electric Power Co.,Ltd.,Hefei 230009,China)

机构地区：[1]国网智能电网研究院有限公司先进输电技术全国重点实验室,北京102209 [2]国网智能电网研究院有限公司电工新材料研究所,北京102209 [3]国网安徽省电力有限公司,安徽合肥230009

出　　处：《轧钢》2025年第1期43-49,共7页Steel Rolling

基　　金：国家电网公司总部科技项目(5500-202158330A-0-0-00)。

摘　　要：为对标欧盟的S355钢材,GB/T 1591—2018要求将原有的Q345钢提升为Q355钢,然而目前国内外对于Q355钢材在高温及冷却后的力学性能研究较少,Q355钢在电力火灾场景下可靠性具有高度不确定性。为此,采用高温共聚焦显微镜组织观察、高温拉伸试验等手段模拟分析了不同加热温度、保温时间和冷却方式条件下Q355B钢力学性能和微观组织的变化规律。研究结果表明:在电力火灾最高温度1100℃时,Q355B钢组织为奥氏体,随着保温时间的增加,晶粒聚合长大并出现退火孪晶,在1100℃保温45min后晶粒尺寸不在变化;在200~1100℃区间,随着加热温度的升高,Q355B钢的屈服强度和抗拉强度显著下降,塑性不断提高,1100℃时,抗拉强度和屈服强度仅为24.9MPa和11.4MPa,而保温时间对其强度影响不大。当加热温度小于800℃时,冷却方式对其力学性能影响不大,当加热温度大于800℃后,水冷试样组织为铁素体、珠光体和马氏体的混合组织且随着加热温度的增加,马氏体比例逐渐增加导致其强度急剧增大。基于实验结果,建立了不同冷却方式下Q355B钢屈服强度、抗拉强度随温度变化的数学模型,为电力火灾下Q355B钢的应用评价提供了参考依据。In order to benchmark the S355steel of the European Union,GB/T 1591—2018requires upgrading the original Q345steel to Q355steel.However,there is currently limited research on the mechanical properties of Q355steel at high temperatures and after cooling both domestically and internationally.The reliability of Q355steel in power fire scenarios is highly uncertain.Therefore,the mechanical properties and microstructure of Q355Bsteel under different heating temperatures,holding time and cooling methods were simulated and analyzed by means of high temperature confocal microscope and high temperature tensile test.The research results show that at the highest temperature of 1100℃in power fires,the microstructure of Q355Bsteel is austenite.With the increase of holding time,the grain aggregates and grows,and annealing twins appear.After holding at 1100℃for 45minutes,the grain size does not change;In the range of 200-1100℃,the yield strength and tensile strength of Q355Bsteel decrease significantly with the increase of heating temperature,and the plasticity increases continuously.At 1100℃,the tensile strength and yield strength of Q355Bsteel are only 24.9MPa and 11.4MPa,and the holding time has little effect on its strength.When the heating temperature is less than 800℃,the cooling method has little effect on its mechanical properties.After the temperature exceeds 800℃,the water-cooled specimen has a mixed microstructure of ferrite,pearlite,and martensite,and as the temperature increases,the proportion of martensite gradually increases,leading to a sharp increase in strength.Based on the experimental results,mathematical models for the yield strength and tensile strength of Q355Bsteel under different cooling methods were established,providing reference basis for the application evaluation of Q355Bsteel in power fire accidents.

关 键 词：Q355钢 电力火灾 力学性能 微观组织 数学模型 应用评价 

分 类 号：TM7[电气工程—电力系统及自动化] TG142.1[一般工业技术—材料科学与工程]