铁磁材料磁记忆检测微观机理研究

Microcosmic Mechanism of Magnetic Memory Testing for Ferromagnetic Materials

对含中心圆孔的Q235平板试样进行静拉伸试验和磁畴组织观察,研究应力集中区和非应力集中区若干测量点处的磁记忆信号和磁畴组织的变化规律。结果表明:随着载荷的增加,磁记忆信号变化幅度增大,局部变形断裂阶段的磁记忆信号幅值小于强化阶段的信号幅值;应力集中区和非应力集中区测量点处的磁记忆信号变化趋势相似,在强化阶段磁记忆信号幅值达到最大值;同一载荷下,应力集中区磁畴分布较非应力集中区更密集,大多数为90°畴壁,磁畴长边较长;同一测量点处,随着载荷变化,从弹性到强化阶段,磁畴分布逐渐密集,180°畴壁逐渐变为90°畴壁,磁畴宽度变小,数量增多,局部变形断裂阶段出现一定量的180°畴壁,磁畴数量减小,宽边的宽度增大。该项研究结论可为探讨磁记忆效应的微观机理提供有效的试验依据。

With the ferromagnetic material Q235 flat sample with a central hole,the static tensile test was done and the magnetic domain was observed.The magnetic memory signals and changes of magnetic domain of several measuring points consisting of stress concentration zones and non-stress concentration zones were studied.The results show that the amplitude of magnetic memory signals increases as the load increases,the amplitude in the local deformation fracture stage is smaller than that in the enhancement stage,and the change tendency of magnetic memory signals at stress concentration zones is similar to that at non-stress concentration zones.The amplitudes of magnetic memory signals in enhancement stage reached the maximum;with the same load,the magnetic domain at stress concentration areas is more intensive.Most of them is 90°domain wall,and the long edge of magnetic domain is longer.At the same point,as the load changes from the elastic stage to enhancement stage,magnetic domain distribution becomes intensive gradually.The 180°domain wall changes into 90°domain wall gradually,the width of magnetic domain becomes smaller,and the number increases.In the local deformation fracture stage,there is a certain amount of 180°domain wall,the number of magnetic domain reduces,and the width increases.The study provides an effective experimental basis for the investigation of the micro mechanism of magnetic memory effect.