“QPQ” is the abbreviation of “Quench-Polish-Quench” in English. The original meaning is quenching – polishing -quenching. It is after the salt bath compound treatment, in order to reduce the surface roughness of the workpiece, the surface of the workpiece can be polished once, and then in the salt bath for oxidation, which is very necessary for precision parts and workpieces with high surface roughness requirements. In China, it is called QPQ salt bath composite treatment technology. QPQ salt bath composite treatment technology can greatly improve the wear resistance and corrosion resistance of the metal surface, while the workpiece almost does not deformation, is a new metal surface strengthening modification technology. This technology realizes the compound of nitriding process and oxidation process; the compound of nitride and oxide; the compound of wear resistance and corrosion resistance; the compound of heat treatment technology and anti-corrosion technology.
At present, QPQ salt bath compound treatment technology has been widely used, especially in automobiles, motorcycles, shaft products, electronic parts, spinning machines, machine tools, electrical switches, industrial molds with very outstanding results.