What should be paid attention to in polishing step in metallographic examination

1. The grinding surface of metallographic specimen should be uniform, and the leveling pressure should be polished on a rotating polishing disc. The pressure should not be too great, and it should continue to reciprocate radially from the edge to the center.

2. The polishing liquid is sprayed continuously during polishing. If there is too much polishing liquid on the polishing flannel, the inclusions in steel and graphite in cast iron will fall off, and the quality of the polished surface will be poor; If there is too little polishing solution, the polished surface will become dim and stained.

3. In the later stage, rotate the sample in all directions on the polishing disc to prevent the inclusions in the steel from tailing.

4. Minimize the possibility of deformation of the polished surface of the metal surface. The polishing time of the whole process should not be too long. After the wear marks are completely eliminated, polishing can be stopped. After the sample is washed with water or alcohol, it can be soaked or directly observed under a metallographic microscope.