Manufacturing method of steel members

The method balances hardness and toughness in steel members by using a hypo-eutectoid composition and controlled nitrogen infiltration, improving bending fatigue and impact strength.

JP7768341B2Active Publication Date: 2025-11-12AISIN CORP
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Patent Information

Application Number
JP2024502903
Authority / Receiving Office
JP · JP
Patent Type
Patents
Current Assignee / Owner
Priority Date
2022-02-24
Filing Date
2023-01-17
Publication Date
2025-11-12
Estimated Expiration
2043-01-17

AI Technical Summary

Technical Problem

Existing methods for manufacturing steel members result in excessively high hardness and low toughness due to the formation of hypereutectoid compositions, leading to vulnerability under impact.

Method used

A method involving a carburizing step with a hypo-eutectoid composition, followed by a nitriding step and quenching process to balance hardness and toughness, including slow cooling and controlled nitrogen infiltration.

Benefits of technology

Improves the balanced hardness and toughness of steel members, enhancing bending fatigue strength and impact strength.

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Patent Text Reader

Abstract

This method for producing a steel member includes: a carburizing step in which an austenitized steel member obtained by heating a steel member to at least an austenization completion temperature is subjected to carbon infiltration at a carbon concentration at which the steel member and carbon form a hypoeuctectic composition, and the carbon-infiltrated steel member is subjected to annealing; and a quenching step in which, after the carburizing step, the steel member is reheated to at least the austenization completion temperature and the heated steel member is rapidly cooled.
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Citation Information

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