二道次高温后Q345B钢的高周疲劳及γ-P-S-N曲线研究  

Study on high cycle fatigue andγ-P-S-N curve of Q345B steel after secondary elevated temperatures

作　　者：葛业豹 缑瑞宾 张春雨[1] 于敏 王念 徐浩 GE Yebao;GOU Ruibin;ZHANG Chunyu;YU Min;WANG Nian;XU Hao(Collage School of Mechanical Engineering,Anhui University of Science and Technology,Fengyang 233100,China;School of Mechanical Engineering,Anhui Polytechnic University,Beijing 100124,China;Faculty of Materials and Manufacturing,Beijing University of Technology,Wuhu 241000,China;Collage of Architecture,Anhui University of Science and Technology,Bengbu 233000,China;Bengbu Special Equipment Supervision and Inspection Center,Bengbu 233000,China)

机构地区：[1]安徽科技学院机械工程学院,安徽凤阳233100 [2]安徽工程大学机械工程学院,北京100124 [3]北京工业大学材料与制造学部,安徽芜湖241000 [4]安徽科技学院建筑学院,安徽蚌埠233000 [5]蚌埠特种设备监督检验中心,安徽蚌埠233000

出　　处：《材料科学与工艺》2025年第2期57-66,共10页Materials Science and Technology

基　　金：安徽省重点研发项目(1604a0902134);安徽高校自然科学研究重点项目(KJ2021A0862);安徽省市场监督管理局科技计划项目(2021MK034)。

摘　　要：为评估二次火灾后钢材的疲劳性能,以工程常用钢Q345B为研究对象,通过不同道次的升温、自然冷却模拟多次火灾环境,采用轴向拉伸与高周疲劳实验,对室温和经历二道次700、800℃高温自然冷却后的Q345B试样的拉伸与疲劳性能进行研究。结果表明:经过高温热处理的Q345B钢屈服平台更为明显;同一道次热处理温度越高,拉伸性能降低越明显。随着热处理温度的升高,组织中珠光体减少,显微组织趋于结构均匀化;在二道次高温自然冷却后Q345B钢微观组织中的珠光体基本消失,显微组织由铁素体组成。根据实验结果,建立二道次高温自然冷却后Q345B钢的中值S-N曲线模型,随着温度的增加,Q345B钢的疲劳强度及寿命下降明显;在同一道次下,不同温度的中值S-N曲线趋于平行。通过采用单侧容限系数法得到基于置信度和试件存活率的安全疲劳设计曲线,即概率γ-P-S-N曲线,利用该模型可对火灾后Q345B钢的疲劳性能进行有效评估。To evaluate the fatigue performance of steel after secondary fires,this paper takes Q345B,a commonly used steel in engineering,as the research object.By simulating multiple fires through different passes of heating and natural cooling,axial static load tensile and high circumferential fatigue tests were conducted to study the tensile and fatigue properties of Q345B specimens at room temperature and after secondary heating at 700 and 800℃followed by natural cooling.The results showed that:the yield plateau of Q345B steel after high temperature heat treatment is more obvious;within the same heat treatment,as the temperature increases,the tensile performance of Q345B steel decreases more significantly and the amount of pearlite in the microstructure decreases,leading to a more homogeneous and uniform microstructure.The pearlite in the microstructure of Q345B steel basically disappears after secondary high temperature natural cooling,and the microstructure is mainly composed of ferrite.According to the test results,the median S-N curve model of Q345B steel after different passes of high temperature natural cooling was established.It is evident that with the increase of temperature,the fatigue strength and life of Q345B steel decreases significantly;under the same pass,the median S-N curves of different temperatures tend to be parallel.The safe fatigue design curve based on confidence and specimen survival rate,i.e.probabilityγ-P-S-N curve,can be obtained by using the one-sided tolerance coefficient method.With this model,the fatigue performance of Q345B steel after fire can be effectively evaluated.

关 键 词：Q345B钢 二道次高温 拉伸疲劳试验 中值S-N曲线 概率γ-P-S-N曲线 

分 类 号：TG157[金属学及工艺—热处理] O346.2[金属学及工艺—金属学]