Nippon Steel Corporation

Masao Onoyama

Mikio Yamanaka

Yasuo Otoguro

Mizuo Sakakibara

Katukuni Hashimoto

Susumu Takemura

Masanobu Tsuji

A boiler tube having improved high temperature strength, improved high temperature corrosion resistance, and resistivity to embrittlement during the service thereof, comprising an outer surface layer and an inner part, the outer surface layer consisting essentially, by weight, of 0.03-0.20% carbon, 1.5-4.0% silicon, 0.1-3.0% manganese, 13-25% chromium, 13-40% nickel, 0.5-3.0% at least one kind selected from the group consisting of molybdenum and tungsten, 0.05-0.5% at least one kind selected from the group consisting of titanium, niobium and vanadium, and the balance iron and inevitable impurities, the inner part consisting essentially, by weight, of 0.03-0.20% carbon, 0.3-1.0% silicon, 0.1-3.0% manganese, 13-25% chromium, 13-40% nickel, 0.5-3.0% at least one kind selected from the group consisting of molybdenum and tungsten, 0.05-0.5% at least one kind selected from the group consisting of titanium, niobium and vanadium, and the balance iron and inevitable impurities. Boron of 0.001-0.01% may be further added to the alloy to improve creep strength while keeping improved high temperature corrosion resistance.

Boiler tube having improved high temperature mechanical strength,

A highly corrosion resistant ferritic stainless steel comprising;

Highly corrosion resistant ferritic stainless steel

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Hikari, Japan

Masao Onoyama