Gas nitrocarburizing and post-oxidation compounded treatment process

Abstract

The invention discloses a gas nitrocarburizing and post-oxidation compounded treatment process. The gas nitrocarburizing and post-oxidation compounded treatment process includes preprocessing the surface of a substrate; performing gas nitrocarburizing to form a diffusion layer on the subsurface of the substrate and a white-bright layer on the surface of the substrate; performing post-oxidation toform an oxidation layer on the surface of the white-bright layer. The technological conditions of gas nitrocarburizing comprises that applied gas is a mixture of NH3, N2 and CO2, the applied temperature is 540-600 DEG C, the treatment duration is 2-4 h and oil cooling is implemented; the technological conditions of post-oxidation comprises that applied gas is a mixture of vapor and nitrogen, the applied temperature is 400-510 DEG C, and the treatment duration is 1-3 h. compared with QPQ (quench-polish-quench) salt bath composite treatment, the gas nitrocarburizing and post-oxidation compoundedtreatment process takes nitrogen, oxygen, carbon dioxide and vapor as the raw materials, thereby being free from pollution, easy to operate and capable of reducing the production cost and greatly improving corrosion resistance and wearing resistance of materials.

Description

technical field [0001] The invention belongs to the technical field of material heat treatment, and in particular relates to gas nitrocarburizing and post-oxidation composite treatment processes. Background technique [0002] QPQ salt bath composite technology refers to low-temperature salt bath nitriding / nitrocarburizing-salt bath oxidation, which realizes the compounding of nitriding process and oxidation process. The structure of the nitrided layer is a compound of nitrides and oxides. compound. The metal surface after QPQ treatment has extremely high wear resistance and corrosion resistance at the same time, so that the wear resistance of ordinary carbon steel reaches more than 10 times that of conventional treatment, and the corrosion resistance reaches more than 20 times that of hard chrome plating treatment, and the workpiece Distortion is minimal. Therefore, QPQ technology has been widely used in industries such as automobiles, locomotives, construction machinery, ...

AI Technical Summary

Problems solved by technology

First of all, nitrogen medium cooling is used in the cooling process, the cooling speed is slow, the cooling time is very long, and the production efficiency is reduced; secondly, for a large number of domestic materials that are pretreated to be normalized, slow cooling will cause needle-shaped ferrite The γ' phase precipitates and reduces the fatigue resistance of the material

Qingdao University of Science and Technology in China is conducting research on ion nitrocarburizing + ion post-oxidation dual composite treatment, but it has not been put into use in production, and there is no relevant report on gas nitrocarburizing + post-oxidation composite treatment technology

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