Vacuum carburizing treatment method and method for manufacturing carburized component

A technology of vacuum carburizing and treatment method, applied in coating, metal material coating process, solid-state diffusion coating, etc., can solve the problems of uneven distribution of surface carbon concentration and carburizing depth, and achieve the inhibition of uneven distribution of carburizing. , The effect of inhibiting the uneven distribution of carburization

Pending Publication Date: 2022-04-12
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At this time, the surface carbon concentration and carburizing depth distribution are uneven
Therefore, the surface layer of the carburized part cannot be maintained at a constant quality

Method used

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  • Vacuum carburizing treatment method and method for manufacturing carburized component
  • Vacuum carburizing treatment method and method for manufacturing carburized component
  • Vacuum carburizing treatment method and method for manufacturing carburized component

Examples

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Embodiment

[0254] Hereinafter, the effects of the vacuum carburizing treatment method according to the present embodiment will be described more specifically using examples. The conditions in the following examples are an example of conditions employed to confirm the feasibility and effect of the vacuum carburizing treatment method of this embodiment. Therefore, the vacuum carburizing treatment method of this embodiment is not limited to this one example of conditions.

[0255] A steel pipe for machine structural use (hereinafter referred to as steel pipe) having a chemical composition corresponding to SCM415 specified in JIS G 4053 (2008) and a round bar corresponding to SCM415 were prepared. The C content of the steel pipes and round bars of each test number was 0.15% by mass. The diameter of the steel pipe is 34mm, the wall thickness is 4.5mm, and the length is 110mm. The round bar has a diameter of 26 mm and a length of 70 mm. The evaluation of the vacuum carburizing treatment was...

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Abstract

Provided is a vacuum carburizing treatment method capable of suppressing uneven carburizing distribution. In an early-stage carburizing step of the vacuum carburizing treatment method according to the present embodiment, when the end time of the carburizing step is defined as ta, the actual carburizing gas flow rate is set to be equal to or greater than the theoretical carburizing gas flow rate at the time of ta / 10 and equal to or less than the theoretical carburizing gas flow rate at the time of 4 seconds from the start of the early-stage carburizing step, and in a later-stage carburizing step, the actual carburizing gas flow rate is set to be equal to or less than the theoretical carburizing gas flow rate at the time of ta / 10. When the initial time at which the acetylene partial pressure becomes 0.8 times or more of the hydrogen partial pressure after the start of the carburizing step is defined as t0 and the actual carburizing gas flow rate at the start of the previous carburizing step is defined as FA, the actual carburizing gas flow rate during the period from t0 to 4t0 is FA [square root of] (t0 / t) or more and FA or less, and the actual carburizing gas flow rate during the period from 4t0 to ta is FA [square root of] (t0 / t) or more and 2FA [square root of] (t0 / t) or less.

Description

technical field [0001] The present invention relates to a vacuum carburizing treatment method and a manufacturing method of carburized parts. In addition, in this specification, the carburized steel part is called a "carburized part." Background technique [0002] Steel parts for which high surface fatigue strength is required are manufactured by subjecting steel materials to surface hardening treatment. One of the surface hardening treatment methods is a vacuum carburizing treatment method. The vacuum carburizing treatment method includes a carburizing step and a diffusion step. In the carburizing step, a carburizing gas that is a hydrocarbon gas is introduced to increase the carbon concentration on the surface of the steel material heated to the carburizing temperature. The hydrocarbon gas is, for example, acetylene, propane, or the like. In the diffusion step, after the carburizing step, the introduction of the carburizing gas is stopped, and carbon is diffused in the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C8/22C21D1/773C21D1/06
CPCC21D1/773C21D1/06C23C8/22
Inventor 藤堂尚二今高秀树
Owner NIPPON STEEL CORP
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