低碳钢塑性变形量磁评定法研究

针对塑性变形量评定的局限问题,基于铁磁材料塑性变形致位错在不同方向分布不同的现象,研究了磁测法在定量评定低碳钢塑性变形量方面的应用前景。实验以工程中常用的低碳钢Q195钢板为测试材料,制作了形状尺寸一致的一批试件,并对其进行了不同程度的塑性变形量加载。通过搭建的磁化检测系统,采用相同强度及频率的正弦波激励,对所有样品进行了不同方向的磁化;同时经线圈及隧道磁敏电阻(TMR)采集了每次磁化的磁化曲线,提取了磁化曲线特征参数,对比了其与塑性变形量的定量关系。结果表明:随着塑性变形量的增加,铁磁钢材在同一磁场强度下产生的磁感应强度也会变大;沿主塑性变形方向磁化时,磁滞消耗能量最少,沿主塑性变形垂直方向磁化时,磁滞消耗的能量最多;磁路内磁场在主塑性变形方向上对塑变量的变化最敏感,而磁路外磁场在主塑变垂直方向上对塑变量的变化最敏感。实现了铁磁材料磁特征参数与塑性变形量的定量关联。本研究为开发简捷的铁磁材料塑性变形量无损评定磁方法奠定了基础。

Studies on magnetic evaluation of plastic deformation of low carbon steel

Aiming at the limitation of plastic deformation evaluation,based on the different distribution of dislocations in different directions of ferromagnetic materials,the application prospects of magnetic measurement in quantitative evaluation of plastic deformation of low carbon steel are studied experimentally.In this experiment,a commonly used carbon steel of Q195 was selected as the testing materials,samples with the same shape and size were made,different level of tensile plastic deformations were introduced into the samples.All samples were magnetized in different directions by using a same strength and frequency sine wave excitation through a magnetic detection system.At the same time,all magnetization curves of each magnetizing process were collected by a coil and a tunnel magneto resistance sensor.Some characteristic parameters of the magnetization curves are extracted,and the quantitative relationship between them and the plastic deformation is compared.①With the increase of plastic deformation,magnetic induction intensity of ferromagnetic steel under the same magnetic field intensity will also increase.②The hysteresis consumes the least energy when magnetized along the main plastic deformation direction;hysteresis consumes the most energy when it is magnetized vertically along the main plastic deformation.③The magnetic field inside the magnetic circuit is most sensitive to the change of plastic variables in the direction of the main plastic deformation,while the magnetic field outside the magnetic circuit is most sensitive to the change of plastic variables in the vertical direction of the main plastic deformation.This study lays a foundation for developing a convenient magnetic NDT method for plastic deformation evaluation of ferromagnetic materials.