Ion nitriding method for efficiently controlling formation of vein-like nitride on surface layer of 38CrMoAl mold

Abstract

The invention relates to an ion nitriding method for efficiently controlling formation of vein-like nitride on the surface layer of a 38CrMoAl mold. The ion nitriding method comprises the steps that the 38CrMoAl mold is put into an ion nitriding furnace, hydrogen is injected, ion sputtering is conducted, and nitrogen continues to be injected; after the temperature is raised to the oxidizing temperature, nitrogen and hydrogen valves are closed, and air is injected; an air valve is closed, the nitrogen and hydrogen valves are opened, and ion nitriding is conducted; and after the temperature is lowered to the room temperature, a sample is taken out. The ion nitriding method has the beneficial effects that an oxidation treating process is additionally conducted before ion nitriding, the nitrogen content of the surface of a workpiece is increased remarkably, the nitrogen concentration gradient of the material surface is increased, diffusing of nitrogen atoms to a substrate is accelerated, no vein-like or net-like nitride exists in a nitride layer, and the surface abrasion resistance and the contact fatigue strength are improved significantly.

Description

technical field [0001] The invention belongs to metal surface chemical heat treatment technology, and relates to an ion nitriding method for efficiently controlling the formation of vein-like nitrides on the surface layer of a 38CrMoAl mold. Background technique [0002] The mold has good comprehensive performance. In order to meet its surface wear resistance, nitriding methods are usually used, mainly including: (1) ion nitriding; (2) salt bath nitriding; (3) gas nitriding, etc. Ion nitriding chemical heat treatment is the earliest developed technology with the widest application range. It has the advantages of uniform nitriding layer, high efficiency, less pollution, short processing time, and small workpiece deformation. It has become an indispensable part of many products. Missing surface strengthening process. [0003] In order to improve the hardness, fatigue resistance and wear resistance of the mold surface, ion nitriding is usually used in China as an effective hea...

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Problems solved by technology

[0003] In order to improve the hardness, fatigue resistance and wear resistance of the mold surface, ion nitriding is usually used in China as an effective heat treatment method to improve the surface performance of the mold at this stage, but due to improper ion nitriding process, there are generally vein nitrides in the nitrided layer , which seriously reduces the surface hardness, wear resistance and wear resistance of the 38CrMoAl nitrided layer, reduces its comprehensive performance, and affects the contact fatigue strength of 38CrMoAl during use

In order to overcome the above defects, in actual production, methods such as repeated rework are generally used to prolong the diffusion method, which eventually leads to the out-of-tolerance depth of the nitriding layer, resulting in serious waste of production costs and other deficiencies.

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