Nippon Steel Corporation

Satoshi Araki

Akihiro Miyasaka

Hiroyuki Ogawa

Tetsuo Ishitsuka

Koichi Takeda

Mizuo Sakakibara

Wataru Murata

Takayoshi Matsui

Kozo Denpo

Koji Takano

Koichi Yoshimura

Hiroyuki Homma

Saburo Kitaguchi

Hiroshi Morimoto

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

An alloy exhibiting corrosion resistance in a combustion environment where V, Na, S and Cl are present comprises, in weight percent, not more than 0.05% C, 0.02-0.5% Si, 0.02-0.5% Mn, 15-35% Cr, 0.5-4% Mo, more than 40% but not more than 60% Co, 5-15% Fe, 0.5-5% W, 0.0003-0.005% Ca and the remainder of Ni at a content of not less than 4% and unavoidable impurities, provided that Cr (%)+0.5Ni (%)+3Mo (%).gtoreq.30 (%). A composite steel tube exhibiting corrosion resistance in a combustion environment where V, Na, S and Cl are present comprises an inner tube constituted of Cr-containing boiler tube and an outer tube constituted of the alloy.

Alloy and composite steel tube with corrosion resistance in combustion

A method of producing clad metal comprises the steps of forming a cladding on the surface of a metal substrate by subjecting powder of a metal which is of a different type from that of the metal substrate and is selected from among Ni-base alloys, Co-base alloys, Ti-base alloys, Fe-base superalloys and stainless steels to hot isostatic pressing under a gas pressure load of not less than 300 Kg/cm.sup.2 at a temperature not higher than the solidus thereof, thereby to obtain a composite material, and elongating the composite material by hot working. Optionally the composite material is subjected to soaking or solution treatment before being subjected to hot working.

Method of producing clad metal

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Yamaguchi-ken, Japan

Satoshi Araki