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Heat treatment nitridation technology for metal

A metal heat treatment and process technology, applied in the direction of metal material coating process, coating, solid diffusion coating, etc., can solve the problems of difficult control of nitrogen potential and performance degradation of mechanical parts, etc., to improve product quality, save energy, penetrate quick effect

Inactive Publication Date: 2010-11-17
SHANGHAI GKN DRIVE SYST
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Problems solved by technology

In the existing hard nitriding technology, the period is generally 24 to 28 hours, and the nitrided layer reaches 0.2 to 0.3mm. During the nitriding process, the nitrogen potential is not easy to control, and the brittle phase is formed due to the high nitrogen potential, which leads to the performance of mechanical parts. decline

Method used

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Embodiment Construction

[0015] The present invention is implemented through the following steps:

[0016] (1) Pre-pumping low vacuum of the workpiece or mold <100MPa;

[0017] (2) (after excluding gases that affect nitriding) fill with pure nitrogen, and uniformly heat to 520-570°C in a circulating nitrogen atmosphere;

[0018] (3) fill with oxygen, so that the metal surface forms a uniform active oxide film in advance;

[0019] (4) In the first stage of nitriding, vacuum pulse inflation-pumping nitriding is carried out with a 1:1 (adjustable) ammonia-nitrogen ratio;

[0020] (5) In the second stage of nitriding, vacuum pulse inflation-pumping nitriding is carried out with a 1:3 (adjustable) ammonia-nitrogen ratio;

[0021] (6) After the nitriding process is completed, low vacuum <100MPa, forced cooling in nitrogen atmosphere, cooling rate ≥10°C / min;

[0022] (7) Cool to below 100°C and take out of the furnace.

[0023] Compared with the prior art, the invention adds an active pre-oxidation proce...

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PUM

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Abstract

The invention discloses a heat treatment nitridation technology for metal. The technology is characterized in that pre-oxidation is carried out before nitridation to form a uniform oxidation film on a metal surface. The technology comprises the following steps: 1) vacuumizing a furnace; 2) charging nitrogen and uniformly heating to 520-570 DEG C; and 3) charging oxygen in the nitrogen atmosphere. In the invention, pre-oxidation is carried out before nitridation so as to form an even active oxidation film on a metal surface layer. The active oxidation film on the metal surface is a core absorbed by initial active nitrogen atoms, so that active nitrogen can be absorbed on the metal surface more effectively to speed up nitridation. Therefore, after the active oxidation film is formed on the metal surface, the nitridation process development has high stability.

Description

technical field [0001] The invention belongs to metal surface heat treatment processing, in particular to a nitriding heat treatment process for iron and steel parts and molds. Background technique [0002] Heat treatment nitriding is nitriding and nitrocarburizing of steel at a temperature of 520°C to 570°C in an atmosphere of ammonia + nitrogen or ammonia + methanol + nitrogen. In recent years, there have been various implementation methods for nitriding and nitrocarburizing processes: for example, pre-vacuuming and filling with ammonia, or ammonia + methanol nitriding treatment process; there is also low vacuum heating first, followed by pulse charging Ammonia gas for nitriding and other processes. In the existing hard nitriding technology, the period is generally 24 to 28 hours, and the nitrided layer reaches 0.2 to 0.3mm. During the nitriding process, the nitrogen potential is not easy to control, and the brittle phase is formed due to the high nitrogen potential, whic...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C8/34
Inventor 张绍贻姚一平徐纲
Owner SHANGHAI GKN DRIVE SYST
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