There are two methods for polishing the inner wall of stainless steel pipes:

Mechanical polishing

Use a throwing rod to extend into the pipe to drive the thousand impeller or homemade abrasive pulley to rotate at high speed , and polishing is performed along with the rotation of the steel pipe itself, and the throwing rod is slowly advanced while rotating. If you feel that the mechanical polishing is not bright enough, you can apply polishing paste appropriately to increase the brightness when fine polishing.

Electrolytic polishing

Electrolytic polishing uses the polished workpiece as the anode and the insoluble metal as the cathode. Both poles are immersed in the electrolytic tank at the same time, and DC electricity is passed through to produce selective anode dissolution. , thereby achieving the effect of increasing the brightness of the workpiece surface.

Mechanical polishing relies on the grinding and rolling action of very fine polishing powder to remove an extremely thin layer of metal on the grinding surface of the sample. If there are deep grinding marks left on the grinding surface before polishing, it will be difficult to remove them only by mechanical polishing.

Because if the grinding marks are thrown away, the polishing fluid must be thickened, the time may be lengthened or the pressure exerted during polishing may be increased, which will cause the metal on the grinding surface to flow and be disturbed, and the deformation layer on the grinding surface of the sample to be thickened. , causing the crystal phase in some alloys to fall off.

Especially when the hardness of aluminum alloy is not too high, the oxidation of the ground surface layer will be more severe, thus affecting the structure observation. Therefore, mechanically polished specimens are only allowed to have fine grinding marks uniform in one direction after fine grinding.