Abstract: A Ni-base heat resistant alloy excellent in weldability and strength at elevated temperatures and suited for use in manufacturing cracking furnace tubes and reformer furnace tubes to be used in ethylene plants as well as a welded joint therefor is provided. The alloy of the invention is a Ni-base heat-resistant alloy, which comprises C: not more than 0.1%, Si: not more than 2%, Mn: not more than 2%, P: not more than 0.025%, S: not more than 0.005%, N: not more than 0.04%, Cr: 10 to 30%, Al: 2.1 to less than 4.5%, and Mo: 2.5 to 15% or W: 2.5 to 9% or Mo and W: 2.5 to 15% in total, and satisfies the relation (1) given below: (104Si+1980P+1980S+9Al+15Ti+11Nb+1.8W+11600B)≦{1.

Abstract: A metallic material of the invention which comprises, in mass %, C: not more than 0.2%, Si: 0.01-4%, Mn: 0.05-2%, P: not more than 0.04%, S: not more than 0.015%, Cr: 10-35%, Ni: 30-78%, Al: not less than 0.005% but less than 4.5%, N: 0.005-0.2%, and one or both of Cu: 0.015-3% and Co: 0.015-3%, with the balance substantially being Fe, and of which the value of 40Si+Ni+5Al+40N+10 (Cu+Co), wherein the symbols of elements represent the contents of the respective elements, is not less than 50 and has excellent corrosion resistance in an environment in which metal dusting is ready to occur and, therefore, can be utilized as or in heating furnace pipes, piping systems, heat exchanger pipes and so forth to be used in a petroleum refinery or in petrochemical plants, and can markedly improve the equipment durability and safety.

Abstract: A Ni-base heat resistant alloy excellent in weldability and strength at elevated temperatures and suited for use in manufacturing cracking furnace tubes and reformer furnace tubes to be used in ethylene plants as well as a welded joint therefor is provided. The alloy of the invention is a Ni-base heat-resistant alloy, which comprises C: not more than 0.1%, Si: not more than 2%, Mn: not more than 2%, P: not more than 0.025%, S: not more than 0.005%, N: not more than 0.04%, Cr: 10 to 30%, Al: 2.1 to less than 4.5%, and Mo: 2.5 to 15% or W: 2.5 to 9% or Mo and W: 2.

Abstract: A heat resistant Ni base alloy comprises, on a mass% basis, 0.1% or less C, 2% or less Si, 2% or less Mn, 0.005% or less S, 10 to 25% Cr, 2.1 to less than 4.5% Al, 0.08% or less N, 0.001 to 1% in total of one or more elements of B: 0.03% or less, Zr: 0.2% or less and Hf: 0.8% or less, and 2.5 to 15% in total of one or more elements of Mo: 0.01 to 15% and W: 0.01 to 9%. The alloy is suitable as a material for a pipe used in ethylene cracking furnace.

Abstract: A stainless steel having excellent corrosion resistance to ozone added water, such as ozone added ultrapure water used in semiconductor manufacturing processes and the like, as well as a manufacturing method. The stainless steel comprises a base metal and an oxide film formed on the surface of the base metal, the base metal being a stainless steel which contains 12 to 30% of Cr, 0 to 35% of Ni, and 1 to 6% of Al and Si while the contents of the other alloying elements are limited to as low a level as possible, the oxide film mainly comprising Al oxide or a Si oxide or both. The oxide film may be formed on the base metal surface through the dry oxidation process or the wet oxidation process. In the stainless steel, metallic ions are rarely dissolved from the base metal into the ozone added water.

Abstract: A high-temperature austenitic stainless steel having improved weldability is disclosed. The steel consists essentially, by weight, of:C: 0.05%-0.15%, Si: less than 1.0%, Mn: 2.0% or less,P: 0.04% or less, S: 0.01% or less, Cr: 20%-30%,Ni: 10%-15%, N: 0.10%-0.30%,B: 0.0010%-0.01%,one or two of La and Ce: 0.01%-0.10% in total,Al: 0.01%-0.20%, anda balance of Fe and incidental impurities, wherein the contents of N and Al satisfy the following inequality:% N+2.times.% Al.ltoreq.0.500%and the value for Ni balance (Ni bal.) of the steel calculated by the following formula is in the range of from -1.0% to +3.0%:Ni bal. (%)=% Ni+0.5.times.% Mn+30.times.(% C+% N)-1.1.times.(% Cr+1.5.times.% Si)+8.2.