METHOD FOR PRODUCING STEEL MEMBER, AND STEEL MEMBER - NIPPON STEEL & SUMITOMO METAL CORP

Title:

METHOD FOR PRODUCING STEEL MEMBER, AND STEEL MEMBER

Document Type and Number:

WIPO Patent Application WO/2018/078844

Kind Code:

A1

Abstract:

This method for producing a steel member includes: a step for heating, in a carburizing atmosphere, a steel sheet so as to form a carburizing layer on the surface of the steel sheet, the steel sheet having a chemical composition containing, in terms of mass%, 0.0005-0.1% of C, 0.01-2.0% of Si, 0.05-3.0% of Mn, 0.9% or less of Al, 0.05% or less of P, 0.01% or less of S, 0.0-0.2% of Ti, 0.0-0.1% of Nb, 0-2% of Cr, 0.0-0.2% of Mo and 0.000-0.005% of B, with the remainder being Fe and impurities, and the steel sheet having a steel structure in which the areal proportion of ferrite is 70% or more; and a step for molding the steel sheet in a metal mold and subjecting the steel sheet to quenching while still housed in the metal mold so as to transform the carburizing layer into martensite and obtain a steel structure in which the areal proportion of ferrite is 50% or more in that part of the steel sheet that is further to the inside than the carburizing layer.

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Inventors:

OKAMOTO RIKI (JP)
KOJIMA NOBUSATO (JP)
HIKIDA KAZUO (JP)
MAEKAWA NORIYUKI (JP)

Application Number:

PCT/JP2016/082222

Publication Date:

May 03, 2018

Filing Date:

October 31, 2016

Export Citation:

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Assignee:

NIPPON STEEL & SUMITOMO METAL CORP (JP)

International Classes:

C21D9/00; B21D22/20; C21D1/18; C22C38/00; C22C38/38; C23C8/22; C23C8/32

Domestic Patent References:

WO2012108460A1

2012-08-16

Foreign References:

JP2014214377A	2014-11-17
JP2005200670A	2005-07-28
JP2000204464A	2000-07-25

Other References: