CASE-HARDENED STEEL HAVING EXCELLENT COLD FORGEABILITY AND CAPABLE OF SUPPRESSING ABNORMAL GRAIN GROWTH DURING CARBURIZING TREATMENT

Title:

CASE-HARDENED STEEL HAVING EXCELLENT COLD FORGEABILITY AND CAPABLE OF SUPPRESSING ABNORMAL GRAIN GROWTH DURING CARBURIZING TREATMENT

Document Type and Number:

WIPO Patent Application WO/2015/146837

Kind Code:

A1

Abstract:

The essence of this case-hardened steel is that it contains prescribed amounts of C, Si, Mn, P, S, Cr, Al, N, Ti, and B, with the density of Ti-containing carbides and carbonitrides having an equivalent circle diameter of 10 nm or greater an less than 200 nm being 10/μm2 or greater, and the density of Ti- and S-containing precipitates having an equivalent circle diameter of 200 nm or greater being 0.2/μm2 or less. The metal structure is a pearlite/ferrite mixed structure, with the area ratio of the mixed structure being 80% or greater, the area ratio of the pearlite being 25% or less of the entire metal structure, and the area ratio of pearlite having an equivalent circle diameter of 100 μm or greater being 10% or less of the entire metal structure.

Inventors:

OKAMOTO NARIAKI
SHINDO YOSUKE

Application Number:

PCT/JP2015/058513

Publication Date:

October 01, 2015

Filing Date:

March 20, 2015

Export Citation:

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Assignee:

KOBE STEEL LTD (JP)

International Classes:

C22C38/00; C22C38/32; C22C38/54; C21D8/06

Foreign References:

JP2008081841A	2008-04-10
JP2012072427A	2012-04-12
JP2005146303A	2005-06-09
JPH1192868A	1999-04-06
JP2010229508A	2010-10-14
JP2012207244A	2012-10-25