Piston QPQ Liquid Nitriding Heat Treatment

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In conclusion, compared with QPQ treatment, deep QPQ treatment has a great improvement in toughness and elongation, which provides a solution to the unqualified elongation of petroleum tubing material after QPQ treatment and the underground fracture of nitrification pipe.

Deep QPQ technology in engineering machinery piston rod, and the application of fasteners on deep QPQ technology is now in large excavators, loaders and other engineering machinery hydraulic piston rod trial application and fasteners, and the results proved that using QPQ technology to deal with the hydraulic piston rod and fasteners, the depth of compound layer, corrosion resistance and surface hardness are meet the technical requirements.

The permeable layer structure is a compound of nitrogen compounds and oxides with high strength and corrosion resistance.The main process is: cleaning → preheating → nitriding → polishing → oxidation → cleaning → drying and oiling, nitriding is the core step of the whole process, its purpose is to form a sufficient thickness of the compound layer and diffusion layer on the metal surface.(1) The brake disc brake is the core of the whole braking system, the brake disc is the key parts of the brake, therefore, its quality directly determines the safety of the tractor in the process of use.

The mechanism of high corrosion resistance of QPQ technology and the X-ray diffraction of deep QPQ treatment of seepage layer of 20 steel sample are shown in Figure 3.Fig. 4 shows the microscopic structure of permeable layer observed under scanning electron microscope after deep QPQ treatment of 20 steel. The outer layer is oxide film, and the inward layer is loose layer, compound layer, intermediate layer and diffusion layer.The loose layer is a part of the compound layer, which is the non-dense part outside the compound layer. with a thickness of 5-10 μm.

Light industry machinery parts QPQ, at present, QPQ salt bath composite treatment technology has also been widely promoted and applied in China, especially in cars, motorcycles, shaft products, electronic parts, spinning machines, machine tools, electrical switches, industrial molds on the use of the effect is very outstanding.”QPQ” metal surface treatment process can replace the chrome plating process, the principle and characteristics of the introduction of two, technical characteristics: good wear resistance QPQ process, metal materials in 570±10℃ working temperature and salt bath liquid reaction, can form a layer of good quality dense compound layer on the metal surface.

QPQ(Quench – Polish – Quench) means quenching – polishing – quenching, from the professional technology, this statement is not exact, this technology is actually low temperature salt bath nitritation plus salt bath oxidation or low temperature salt bath nitritation plus salt bath oxidation, in China called QPQ technology QPQ salt bath compound treatment technology.QPQ technology is a kind of metal surface modification technology, with high corrosion resistance, high wear resistance, pollution-free characteristics.In the mid-1980s, our company independently developed QPQ technology, which broke the status quo of foreign monopoly, and quickly put into large-scale production in China.

The statistical analysis method of corrosion data for piston QPQ processing provides a method for designing corrosion test, analyzing corrosion data, and determining the confidence of corrosion data. It is mainly used for analyzing and counting corrosion conditions, rather than for determining the quality of a specific product.Stainless steel salt spray test in practical application, stainless steel salt spray test is the most widely known – this material salt spray test can reach how many hours?Practitioners are no stranger to this problem.Material manufacturers usually use passivation or improve the level of surface polishing methods, to improve the stainless steel salt spray test time.But the most critical determinant is the composition of stainless steel itself, that is, the content of metal elements.Facts: standard 304, neutral salt spray generally between 48 and 72 hours;Standard 316, neutral salt spray generally in 72 ~ 120 hours.