Metallographic analysis is a routine inspection method to evaluate the quality of metal materials according to relevant standards and regulations, and can be used to judge whether the production process of parts is perfect, which is helpful to find out the causes of defects of parts. It is an indispensable means to ensure product quality. In general, the preparation of metallographic samples should go through the following steps: sampling, inlay, polishing (rough and fine grinding) and polishing. On site metallographic inspection is to select inspection points directly on the workpiece without damaging the tested object, and carry out polishing & mdash; polishing & mdash; erosion and other processes, so as to ensure the integrity of the workpiece, and use a portable metallographic microscope to observe the metallographic structure. The on-site metallography is now widely used in electric power, metallurgy, petrochemical, large machinery, casting and forging, heat treatment and scientific research units for conventional metallographic observation and photography of large workpieces, as well as for the detection of small particles, powder foam and large-area silicon wafers.