加载条件下铁磁材料疲劳裂纹扩展自发射磁信号行为研究

来源期刊：金属学报2011年第3期

论文作者：徐滨士 董丽虹 董世运 薛楠

文章页码：257 - 262

关键词：金属磁记忆； 疲劳裂纹； 加载； 磁异变峰； 磁荷

Key words：metal magnetic memory； fatigue crack； loading； abnormal magnetic peak； magnetic charge

摘    要：研究了45CrNiMoVA铁磁钢中心裂纹试样加载条件下疲劳裂纹扩展过程中表面自发射磁信号的变化规律.结果表明:承受疲劳载荷前,各检测线呈现初始磁异变峰特征,切口中心检测线具有最大异变峰-峰值;加载后但疲劳裂纹萌生前,切口位置磁性反转,显示一次异变峰特征,远离切口检测位置磁信号呈现线性;疲劳裂纹扩展过程中,各检测线依次呈现二次异变峰;二次异变峰-峰值和正负峰间斜率可以动态表征疲劳裂纹扩展寿命.基于磁荷概念和等效磁场理论分析了加载条件下疲劳裂纹扩展自发射磁信号行为.

Abstract: Variations of self-emitting magnetic signals during fatigue crack propagation of center-cracked tension (CCT) specimen of 45CrNiMoVA steel were studied.The results showed that the initial abnormal magnetic peak occurred in all the measured lines,and there was a maximum peak-to-peak value in the center measured line before loading.However,the first abnormal magnetic peak occurred on the position of the precut notch after loading,while magnetic signal curve presented linearity on the position without precut notch,at this time fatigue crack did not initiate.During fatigue crack propagation,the second abnormal magnetic peak occurred in the measured lines in turn.The peak-to -peak value of the second abnormal magnetic signals and the slope coefficient between peak-to-peak can be used to characterize fatigue crack propagation life dynamically.The behavior of self-emitting magnetic signals during fatigue crack propagation was analyzed on the basis of magnetic charge and effective magnetic field theory under loading condition.