Nippon Steel Corporation

Katukuni Hashimoto

Yasuo Otoguro

Toshio Fujita

Hisashi Takahashi

Mikio Yamanaka

Mizuo Sakakibara

Masao Onoyama

A high-strength, heat-resisting ferritic steel pipe or tube for boiler use containing 0.03 to 0.15% C, 0.1 to 1.5% Mn, 8 to 13% Cr, 1.8 to 3.0% W, 0.05 to 0.30% V, 0.02 to 0.12% Nb, 0.02 to 0.05% N, 0.02 to 0.4% Mo, and up to 0.25% Si. This pipe or tube has an improved high-temperature creep rupture strength and an excellent weldability and toughness.

High-strength heat-resisting ferritic steel pipe and tube

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 ferritic heat-resisting steel with an excellent toughness comprises

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Sagamihara, Japan

Katukuni Hashimoto