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

发展了一种先进的磁性无损测量技术--巴克豪森噪声(BHN)分析方法，用于评价铁磁材料的强度和表征其微观结构特性。BHN测量系统由分析BHN的装置和位于磁化芯极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)的环路中获取斜率参数(表观磁导率)，可以在比BHN测量更宽的范围内评估应力水平。其次，利用数字光谱仪对疲劳轧辊材料的损伤过程和铬钼合金钢的退化进行了BHN分析。对于视频和使用过的材料，FFT频谱的明显差异被识别出来。此外，BHN还可以评估焊接构件中的残余应力和石墨铸铁的性能。因此，研制的混合式BHN测量系统可以同时提供有关材料强度性质的两种信息，即铁磁材料的“应力状态”和“微结构质量”。它似乎有多种可能性，可以进行广泛的、多边的材料评估。

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.