钢结构工程中主要的检测内容包括:构件尺寸及平整度的检测、构件表面缺陷的检测、连接(焊接、螺栓连接)的检测、钢材锈蚀检测、防火涂层厚度检测等。其中,磁粉探伤法是检测构件表面缺陷的方法之一。磁粉探伤的基本原理如下:外加磁场对构件(只能是铁磁性材料)进行磁化后,若构件上不存在缺陷,则它各部位的磁特性基本一致;若构件上存在裂纹、气孔或非金属物夹渣等缺陷时,就会在构件上造成气隙或不导磁的间隙,使缺陷 The main contents of steel structure testing include: component size and flatness testing, component surface defects detection, connection (welding, bolting) testing, steel corrosion detection, fire protection coating thickness testing. Among them, magnetic particle inspection is one of the methods to detect the surface defects of components. The basic principles of magnetic particle inspection are as follows: Magnetic field component (only ferromagnetic material) after magnetization, if there is no defect on the component, then its parts of the magnetic properties are basically the same; if there are cracks on the components, pores or non-metallic Things slag and other defects, it will cause air gap components or not magnetic gap, so that defects