Nitriding treatment method and manufacturing method of nitrided part

A technology of nitriding treatment and gas nitriding, which is applied in the direction of coating, metal material coating process, solid-state diffusion coating, etc., and can solve the problems of increased man-hours for fixture operations and insufficient hardened layer depth.

Inactive Publication Date: 2018-02-13
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, depending on the required properties, a sufficient hardened layer depth may not be obtained
In addition, as in the proposal in Patent Document 2, when a non-nitriding jig is prepared for fluoridation treatment, new problems arise in the selection of jigs and the increase in man-hours.

Method used

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  • Nitriding treatment method and manufacturing method of nitrided part
  • Nitriding treatment method and manufacturing method of nitrided part
  • Nitriding treatment method and manufacturing method of nitrided part

Examples

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Embodiment

[0127] JIS standard SCr420 (JIS G 4053 alloy steel steel for machine structure) and S45C (JIS G 4051 carbon steel steel for machine structure) were melted in a 50 kg vacuum melting furnace to produce molten steel. Molten steel is cast to create ingots. The ingot was hot forged to produce a steel bar with a diameter of 20 mm.

[0128] For bar steel of SCr420, quenching and tempering are performed after performing normalizing treatment in order to homogenize the structure. In the normalizing treatment, the bar steel was heated to 920° C., held for 30 minutes, and then air-cooled. In the quenching treatment, the bar steel was heated to 900° C., held for 30 minutes, and then water-cooled. During the tempering treatment, the steel bar was kept at 600° C. for 1 hour.

[0129] For the steel bar of S45C, it is heated to 870°C and kept for 30 minutes, and then air cooled.

[0130] A test piece of 15 mm x 80 mm x 5 mm was collected from the produced bar steel by machining.

[0131]...

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Abstract

Provided is a method for nitriding a low alloy steel with which a certain hardened case depth can be ensured and formation of a compound layer can be inhibited. A low alloy steel is heated to a temperature ranging from 550 to 620°C, and a high K N value process and low K N value process are performed for a total process time of A ranging from 1.5 to 10 hours. In the high K N value process, a nitriding potential K NX given by Formula (1) ranges from 0.15 to 1.50, the average K NX value K NXave ranges from 0.30 to 0.80, and the process time is X in hours. In the low K N value process, which is performed after the high K N value process, a nitriding potential K NY given by Formula (1) ranges from 0.02 to 0.25, the average K NY value K NYave ranges from 0.03 to 0.20, and the process time is Y in hours. An average nitriding potential value K Nave determined by Formula (2) ranges from 0.07 to 0.30. K Ni = NH 3 partial pressure / H 2 partial pressure 3 / 2 K Nave = X × K NXave + Y × K NYave / A where i is X or Y.

Description

technical field [0001] The present invention relates to a nitriding treatment method and a method for manufacturing a nitrided component, and more specifically, relates to a method for nitriding low-alloy steel and a method for manufacturing a nitrided component. Background technique [0002] For steel parts used in automobiles, various industrial machines, etc., in order to improve mechanical properties such as fatigue strength, wear resistance, and adhesive wear resistance, the surface is subjected to carburizing and quenching, induction hardening, nitriding, and soft nitriding. Hardening heat treatment. Nitriding treatment and nitrocarburizing treatment at a heating temperature of A 1 The ferrite region below the point is heat treated without using phase transformation. As a result, heat treatment deformation can be reduced. Therefore, nitriding and nitrocarburizing are often used for parts with high dimensional accuracy, large parts such as gears used in transmission ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23C8/26C21D1/06
CPCC21D1/06C21D1/76C23C8/26
Inventor 梅原崇秀大藤善弘
Owner NIPPON STEEL CORP
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