提出以磁巴克豪森（MBN）信号检测铁磁材料中碳含量的方法，用退火处理后的碳素钢得到硬度、MBN信号与碳含量的关系。硬度随碳含量增大而增大，MBN特征值随碳含量的增大先增大后减小，在碳质量分数为0.55%时，MBN特征值能取得最大值。将45钢通过不同回火温度处理得到不同硬度的试样，发现MBN信号随硬度增大逐渐递减。对比可知，碳含量的变化对MBN信号存在很大影响。若被测试样碳质量分数在0.32%~0.55%或0.55%~0.80%间时，MBN信号随碳含量单调递增或递减，可由MBN信号直接测得碳的质量分数。当被测样品碳含量介于0.32%~0.80%间时，同一MBN特征值对应着两个碳质量分数，可将MBN信号测量和硬度测量相结合，实现基于磁巴克豪森信号的碳质量分数的无损评估。

Any factors affecting the microstructure would cause the magnetic Barkhausen noise change, therefore, a new method to detect carbon content of ferromagnetic materials based on Barkhausen signal was proposed in this paper. The annealed carbon steels were used to investigate the dependence of hardness and MBN signal on carbon content. The hardness increases with the increasing carbon content, and the characteristic values of the MBN increases initially and then decreases with the increase of carbon content, reaching a maximum value at 0.55%. The 1045 carbon steels with different hardness were obtained by treating with different tempering temperatures, finding that the MBN decreases gradually with the increasing hardness. By contrast, the effect of carbon content on the MBN is not only caused by hardness, but also by carbon content itself. When the carbon content of the sample to be measured is in the range of 0.32%~0.55% or 0.55%~0.80%, the MBN signal increases or decreases monotonically with the carbon content, and the carbon content can be measured directly by the MBN signal. When the carbon content is between 0.32% and 0.80%, the MBN measurement and hardness measurement can be combined to achieve a nondestructive evaluation of carbon content.