中文摘要：

由U型铁芯和构件的被测部分构成了一个闭合磁路，在U型铁芯上缠绕激励线圈和感应线圈，由激励线圈中的电流信号与感应线圈中的电压信号测绘出不同应力条件下被测试样的未饱和磁滞回线，得出试样矫顽力垃与外加拉应力、由塑性变形引起的残余应力之间的关系。外加拉应力使材料的矫顽力Hc减小，而残余应力在材料内部产生位错的钉扎效应使矫顽力Hc增大。冷作硬化过程中，材料矫顽力Hc的变化为外加应力与残余应力综合作用的结果。

英文摘要：

A magnetic yoke containing an induced coil and indirect pickup coil along with a part of the sample make up a closed magnetic circuit. The magnetic minor hysteresis loops of a low carbon steel sample were measured by using voltage signal from pickup coil and current signal from induced coil. As a result, the relationship between coercive force Hc and the applied stress, as well as the effect of residual stress on the coercive force Hc was obtained. It was found that in the elastic region, the eoercity is inclined to decrease when there is an increase of external stress due to domain reorientation, while in the plastic stage, it increases almost proportionally with the increase of external stress as a result of dislocation pinning effect. After the cold working, the variation in Hc is attributed to the joint effects of the applied stress and residual stress on domain wall motion.