Material Evaluation of the Strenght and Degradation of Ally Steels by Magnetic Barkhausen Noise Analysis

采用先进的磁性无损测量技术“巴克豪森噪声分析”（Barkhausen noise analysis， BHN）方法，对铁磁材料的强度和微观结构特性进行评估和表征。该测量系统由巴克豪森噪声分析装置和位于磁化磁芯中心的小测量线圈的磁感应电压积分电路组成。从磁化电流（Hs）与测量电压（Bs）的回路中取斜率参数（视磁导率），可以在比BHN测量更宽的范围内评估应力水平。接下来，通过BHN分析，通过数字频谱分析仪检测(1)疲劳轧辊材料的损伤过程(2)Cr-Mo合金钢的退化。在FFT频谱的明显差异被识别为新的和使用的材料。此外，还可以利用BHN对焊接构件的残余应力和石墨铸铁的性能进行评价。因此，所开发的混合型BHN测量系统可以同时提供铁磁材料的“应力状态”和“微观结构质量”两种材料强度特性信息。它似乎具有更广泛的多边评价的各种可能性。

Advanced magnetic non-destructive measurement technique, "Barkhausen noise (BHN) analysis" method is developed for ecaluating the strength and characterizing the mictostructural properties of ferromagnetic materials Thie BHN measuring system consists of the devices for analyzing BHN and circuit for integrating magnetic induced voltage of small measuring coil located in the center of magnetizing core poles. Taking a parameter of the slope, (apparent permeability) from the loop of magnetizing current(Hs) v.s. measuring voltage(Bs), if enables to evaluate the stress level in more wider tange then BHN measurement. Next, BHN analysis is performed to detect (1) the damaging process in fatigued roller material,(2) the degradation of Cr-Mo alloy steels by digital spectrum analyzer. Distinct differences in FFT spectrum are recobnized for the viegin and used material. Moreover, residual stresses in the welded component and the property of graphite cast iron are also able to be evaluated by BHN. In consequence, the developed hybrid-type BHN measuring system can provide us simultaneously the two informations about the properties of material stength, namely, "stress state" as wsell as "microstructural quality" of ferromagnetic materials. Is seems to have the various possibility for mowe wide and multilateral matireal evaluation.