QPQ treatment technology, which is the short form of Quench-polish -Polish-Quench. It means to put theblack metal parts into two kinds of salt bath with different properties, through various elements infiltration intothe metal surface to form composite infiltration layer, so as to achieve the purpose of surface modification ofthe parts. It has not been hardened, but the effect of surface quenching, so it is called QPQ at home andabroad. QPQ treatment is a kind of compound treatment technology. Heat treatment and anti-corrosiontreatment are completed at one time with low temperature and short time. It can improve the surfacehardness, wear resistance and corrosion resistance of the part at the same time, and reduce frictioncoefficient. It has the advantages of optimizing processing procedures, shortening production cycle andreducing production cost, which has been recognized and praised by many manufacturers, such as AmericanGE, GM, Volkswagen of Germany, mercedes-benz, Toyota of Japan, Honda and other famous multinationalcompanies, which have been largely adopted. This technology is regarded a great progress in the field ofmetal surface strengthening technology by the heat treatment industry at home and abroad. It is called as arevolutionary new technology in the field of metallurgy.