应变幅对低层错能Fe-Mn-Si系合金室温低周疲劳性能的影响  

Effect of Strain Amplitude on Low Cycle Fatigue Properties at Room Temperature of Low Stacking-Fault-Energy Fe-Mn-Si Alloy

作　　者：管前庆 杨蔚涛 杨旗 GUAN Qianqing;YANG Weitao;YANG Qi(Shanghai Key Laboratory of Engineering Materials Application and Evaluation,Shanghai Research Institute of Materials Co.,Ltd.,Shanghai 200437,China)

机构地区：[1]上海材料研究所有限公司,上海市工程材料应用与评价重点实验室,上海200437

出　　处：《机械工程材料》2024年第7期41-47,共7页Materials For Mechanical Engineering

基　　金：上海市中央引导地方科技发展资金资助项目(YDZX20223100003003)。

摘　　要：在低加载应变速率(8×10^(−3) s^(−1))下对退火态低层错能Fe-29.4Mn-4.3Si-1.4Al-0.049C合金进行室温低周疲劳试验,研究了不同应变幅(1%,2%,3%)下合金的低周疲劳性能以及疲劳断裂后的微观结构,揭示应变幅对低周疲劳变形行为和疲劳寿命的影响规律和作用机制。结果表明:随着应变幅的增加,试验合金的疲劳寿命显著缩短,疲劳变形行为均表现出初始循环硬化、循环饱和、二次循环硬化的三阶段加工硬化特征;增大应变幅会增加循环加工硬化程度及其随循环次数的增加速率,缩短初始循环硬化阶段和循环饱和阶段。随着应变幅的增加,试验合金中的ε马氏体平均转变速率增大,疲劳断裂后组织中不可逆块状ε马氏体含量增多,尺寸增大,且组织内部应变分布的不均匀程度增大。试验合金的疲劳变形机制为Shockley不全位错的平面滑移和ε马氏体的相变及逆相变。增大应变幅会提高疲劳变形的平均峰值应力,促进Shockley不全位错分离和块状ε马氏体生成,增大块状ε马氏体的尺寸,削弱ε马氏体相变可逆性和变形可逆性。Low-cycle fatigue tests at room temperature were carried out on annealed low stacking-fault-energy Fe-29.4Mn-4.3Si-1.4Al-0.049C alloy at low loading strain rate(8×10^(−3) s^(−1)).The low-cycle fatigue properties and microstructure after fatigue fracture were studied at different strain amplitudes(1%,2%,3%),and the effecting law and action mechanism of strain amplitude on low-cycle fatigue deformation behavior and fatigue life were revealed.The results show that with the increase of strain amplitude,the fatigue life of the test alloy decreased significantly,and the fatigue deformation behavior showed three stages of work hardening characteristics,including initial cycle hardening,cycle saturation and secondary cycle hardening.Increasing the strain amplitude would increase the cycle hardening degree and the rate of increase with the number of cycles,and shorten the initial cycle hardening stage and cycle saturation stage.With the increase of strain amplitude,the average transformation rate ofεmartensite in the test alloy increased,the content and size of irreversible massiveεmartensite in the microstructure increased after fatigue fracture,and the irregularity degree of strain distribution in the microstructure increased.The fatigue deformation mechanism of the test alloy was plane slip of Shockley partial dislocation and phase transition and reverse phase transition ofεmartensite.Increasing strain amplitude could increase the mean peak stress of fatigue deformation,promote Shockley partial dislocation separation and formation of massiveεmartensite,increase the size of massiveεmartensite,and weaken the reversibility ofεmartensite transformation and deformation.

关 键 词：低层错能Fe-Mn-Si合金 低周疲劳性能 Ε马氏体相变 应变幅 

分 类 号：TG142.1[一般工业技术—材料科学与工程]