Nippon Steel Corporation

Wataru Murata

Yuichi Kato

Mikio Yamanaka

Keiichi Ohmura

Hidehiko Sumitomo

Masayuki Kasuya

Jiro Tominaga

Masuhiro Fukaya

Fumio Fudanoki

Mizuo Sakakibara

Satoshi Araki

Masahiro Ito

Koichi Yoshimura

Takayoshi Matsui

Koji Takano

Hitoshi Ota

Wataru Shinada

Jun Nakatuka

Jun Araki

High strength martensitic stainless steel having high rusting resistance which comprises, by weight, 0.13 to 0.20% of C, 0.5 or less of Si, 2.0% or less of Mn, 1.0 to 2.5% of Ni, 12.0 to 16.0% of Cr, 1.3 to 3.5% of Mo, 0.06 to 0.13% of N, if necessary, 0.001 to 0.010% of B, or 0.05 to 1.0% of Ti, 0.05 to 1.0% of Nb, which satisfies 16 to 21% of ARI value for a rusting resistance index (Formula (1)), less than 0% of DI value for a .delta.-ferrite content index (Formula (2)), less than 0% of MI value for martensite content index (Formula (3)), less than 260% of W.sub.1 or W.sub.2 value for a cold workability index (Formulas (4) or (5)), with the balance comprising substantially Fe and inevitable impurities, said steel being characterized in that the martensite structure or the tempered martensite structure is contained, in which a Cr carbide of 0.2 .mu.m or less in grain size is deposited, especially enabling to produce a self drilling-tapping screw superior in screwing ability and rusting resistance, a nail superior in driving ability and rusting resistance, a cutter having high rusting resistance, a high strength spring superior in rusting resistance, etc.

High strength martensitic stainless steel having superior rusting

High-strength stainless steel foil for corrugating and process for

Method for direct heat treating austenitic stainless steel wire rod wherein a hot rolled austenitic stainless steel wire rod is rendered to finish the final finishing stand of a hot rolling mill at a temperature zone in the range of solution heat treatment, then the temperature zone of said solution heat treatment is so maintained that the austenitic crystal grain size is to be less than 7.0, and subsequently said wire rod is quenched to a temperature where no chromium carbide is precipitated at a cooling rate where no chromium carbide is precipitated.

Method for direct heat treating austenitic stainless steel wire rod

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Hikari, Japan

Wataru Murata