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Stainless steel bCr13Mo gas nitriding process

A gas nitriding, stainless steel technology, applied in metal material coating process, coating, solid-state diffusion coating, etc., can solve environmental pollution, energy consumption and other problems

Inactive Publication Date: 2008-03-12
WUJIANG TIANDIREN VACUUM FURNACE
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  • Application Information

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Problems solved by technology

[0002] With the acceleration of the development of the machinery industry, some wear-resistant stainless steel materials are widely used, such as key parts of automobile engines, anti-corrosion and wear-resistant parts in the machinery industry, etc. In order to improve the wear resistance and service life of these parts, the common method is Plating hard chrome on the surface of the workpiece, but this process brings great energy consumption and environmental pollution

Method used

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Embodiment Construction

[0004] Due to Cr 2 o 3 Easy to form Cr on the surface 2 o 3 The passivation film will seriously hinder the infiltration of N atoms. To form an excellent nitrided layer on the workpiece, NH4CL must be destroyed. In order to solve the above problems, the present invention adds a small amount of NH4CL in the nitriding process. NH4CL will be decomposed into HCl when heated, HCl and Cr 2 o 3 Reaction to achieve the purpose of eliminating the passivation film. In this process, the ammonia decomposition rate can be maintained at about 25%, and the nitriding temperature is 520°C. Before the end of carburizing, the temperature can be increased to 530°C, and a certain period of denitrification treatment is performed to reduce the hardness of the surface carburized layer. At the same time , You can also increase the depth of the nitriding layer. The specific nitriding time can be controlled according to the requirements of the workpiece. Generally, it is controlled at about 10 hours...

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Abstract

The invention provides a gas nitriding process for stainless steel bCr13Mo, which is a surface treatment method in the field of heat treatment. As bCr13Mo is liable to forming a dense Cr2O3 passivated layer, nitriding is difficult by an ordinary way. The invention adds small amount of NH4Cl during nitriding to heat NH4Cl, which dissolves HCl to react with bCr13Mo so as to damage the passivated layer of bCr13Mo, hence N atoms can rapidly permeate into bCr13Mo. During the process, the dissolution rate of ammonia maintains at about 25%, the nitriding temperature is 520 DEG C. Before carburization ends, the temperature can be improved to 530 DEG C to carry out certain time of de-nitrogenizing, so as to reduce the surface hardness of the bCr13Mo and increase the depth of the nitrided layer. The actual time can be managed according to the requirement of the work piece. Generally the time under 520 DEG C is about 10 hours, that under 530 DEG C is about 2 hours, and then the work piece is discharged to cool rapidly.

Description

technical field [0001] The invention belongs to the field of heat treatment industry, especially a nitriding process of bCr13Mo material Background technique [0002] With the acceleration of the development of the machinery industry, some wear-resistant stainless steel materials are widely used, such as key parts of automobile engines, anti-corrosion and wear-resistant parts in the machinery industry, etc. In order to improve the wear resistance and service life of these parts, the common method is Hard chrome is plated on the surface of the workpiece, but this process brings great energy consumption and environmental pollution. Therefore, it is our urgent problem to be solved not only to ensure the high wear resistance of the workpiece, but also to achieve non-toxic and environmental protection. Contents of the invention [0003] The present invention changes the chromium plating on the surface of the workpiece to the surface nitriding method. Under normal conditions, b...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C8/26C23C8/02
Inventor 李荣华
Owner WUJIANG TIANDIREN VACUUM FURNACE
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