A manufacturing method of a grain-oriented electrical steel sheet according to an embodiment of the present invention, includes: manufacturing a cold-rolled sheet; forming a groove by irradiating a laser beam on the cold-rolled sheet; and partially removing an oxide layer formed on a surface of the cold-rolled sheet so that a thickness of the oxide layer remains at 1 to 5 nm, wherein the grain-oriented electrical steel sheet has islands of 0.25 or less having sphericity of 0.5 to 0.9 under the oxide layer under the groove.

A furnace for annealing a sheet includes: a first section; a second vertical section, the second vertical section including openings supplied with an oxidizing medium, an opening facing each side of the sheet, and means for separately controlling a flow of the oxidizing medium on each side of the sheet; and a third section. The second vertical section is located in a distinct casing and separated from the first and third sections with sealing devices. The second vertical section includes extraction openings for extracting the oxidizing medium not consumed by the sheet, an extraction opening facing each side of the sheet. The openings supplied with an oxidizing medium are located transversally at one end of the second vertical section. The extraction openings are located transversally at an other end of the second vertical section.

A furnace for annealing a sheet includes: a first section; a second vertical section, the second vertical section including openings supplied with an oxidizing medium, an opening facing each side of the sheet, and means for separately controlling a flow of the oxidizing medium on each side of the sheet; and a third section. The second vertical section is located in a distinct casing and separated from the first and third sections with sealing devices. The second vertical section includes extraction openings for extracting the oxidizing medium not consumed by the sheet, an extraction opening facing each side of the sheet. The openings supplied with an oxidizing medium are located transversally at one end of the second vertical section. The extraction openings are located transversally at an other end of the second vertical section.

A method for controlling surface reactions on a steel strip running through a furnace includes, successively, a first section, a second section, and a third section separated by a sealing element, an atmosphere in the second and third sections being oxidizing and reducing respectively, the method including: heating, in the first section, the steel strip to between 600 and 750° C., while causing the atmosphere therein to be slightly oxidizing and to include: an H.sub.2 content inferior to 2%; an O.sub.2 content inferior to 0.1%; an H.sub.2O or CO.sub.2, or H.sub.2O+CO.sub.2 content superior to 0.03%; a controlled dew point ranging from −50 to −15° C.; and a controlled concentration of CO+CO.sub.2 maintained below 2%. All percentages are expressed in terms of volume.

A method for laser-processing a metallic surface to produce a functionalized metallic surface comprises: providing a substrate having the metallic surface; applying a pulsed laser beam with a controlled fluence to a region of the metallic surface in an environment containing oxygen, wherein metal material in the region of the metallic surface ablates due to the applied pulsed laser beam and wherein at least a portion of the ablated metal material oxidizes and redeposits on the metallic surface to produce one or more oxidized-metal-coated structures; wherein the metallic surface having the one or more oxidized-metal-coated structures is the functionalized metallic surface. Optionally, the functionalized metallic surface has a higher hemispherical emissivity than the metallic surface free of the oxidized-metal-coated structures and prior to applying the pulsed laser beam under otherwise identical conditions. Optionally, the functionalized metallic surface is characterized by a hemispherical emissivity of at least 0.85.

Provided is a black stainless steel sheet that has excellent weldability, that can ensure good toughness and corrosion resistance, and that can maintain the blackness of the surface thereof, even after being welded. This black ferrite-based stainless steel sheet having excellent weldability includes, as a base, a stainless steel containing, in mass %, 0.020% or less of C, 1.0% or less of Si, 0.35% or less of Mn, 0.04% or less of P, 0.005% or less of S, 11-25% of Cr, 1.0% or less of Mo, 0.020% or less of N, 0.4% or less of Al, 10(C+N) to 0.3% of Ti, 0.05% or less of Nb, and 0.01% or less of O, and has a surface in which an oxide coating is formed on the base, wherein the surface has a lightness index (L*) satisfying L*≤45, chromaticity indices (a*, b*) satisfying −5≤a*≤5 and −5≤b*≤5, and a blackness (E) satisfying E=(L*2+a*2+b*2)1/2≤45.

Provided is a black stainless steel sheet that has excellent weldability, that can ensure good toughness and corrosion resistance, and that can maintain the blackness of the surface thereof, even after being welded. This black ferrite-based stainless steel sheet having excellent weldability includes, as a base, a stainless steel containing, in mass %, 0.020% or less of C, 1.0% or less of Si, 0.35% or less of Mn, 0.04% or less of P, 0.005% or less of S, 11-25% of Cr, 1.0% or less of Mo, 0.020% or less of N, 0.4% or less of Al, 10(C+N) to 0.3% of Ti, 0.05% or less of Nb, and 0.01% or less of O, and has a surface in which an oxide coating is formed on the base, wherein the surface has a lightness index (L*) satisfying L*≤45, chromaticity indices (a*, b*) satisfying −5≤a*≤5 and −5≤b*≤5, and a blackness (E) satisfying E=(L*2+a*2+b*2)1/2≤45.

The present invention provides a cast product that can further enhance the stability of a barrier layer and can exhibit further superior oxidation resistance, carburization resistance, nitriding resistance, and corrosion resistance, when used under a high-temperature atmosphere, the cast product having a surface with a barrier layer comprising an Al-containing metal oxide expressed in (Al.sub.(1-x)M.sub.(x)).sub.2O.sub.3, where M is at least one of Cr, Ni, Si, and Fe, wherein the Al-containing metal oxide includes a solid solution of at least one of Cr, Ni, Si, and Fe with Al, in a relationship of Al/(Cr+Ni+Si+Fe)≥2.0 in an atomic % ratio, the barrier layer being composed of two layers consisting of a first Al-containing metal oxide layer and a second Al-containing metal oxide layer formed between the surface of the cast product and the first Al-containing metal oxide layer, and the second Al-containing metal oxide layer being greater than the first Al-containing metal oxide layer with respect to the atomic % ratio of Al/(Cr+Ni+Si+Fe), and having a thickness that is at least one fifth of a thickness of the barrier layer.

The present invention provides a cast product that can further enhance the stability of a barrier layer and can exhibit further superior oxidation resistance, carburization resistance, nitriding resistance, and corrosion resistance, when used under a high-temperature atmosphere, the cast product having a surface with a barrier layer comprising an Al-containing metal oxide expressed in (Al.sub.(1-x)M.sub.(x)).sub.2O.sub.3, where M is at least one of Cr, Ni, Si, and Fe, wherein the Al-containing metal oxide includes a solid solution of at least one of Cr, Ni, Si, and Fe with Al, in a relationship of Al/(Cr+Ni+Si+Fe)≥2.0 in an atomic % ratio, the barrier layer being composed of two layers consisting of a first Al-containing metal oxide layer and a second Al-containing metal oxide layer formed between the surface of the cast product and the first Al-containing metal oxide layer, and the second Al-containing metal oxide layer being greater than the first Al-containing metal oxide layer with respect to the atomic % ratio of Al/(Cr+Ni+Si+Fe), and having a thickness that is at least one fifth of a thickness of the barrier layer.

The present disclosure relates to an oxidation-resistant heat-resistant alloy and a preparing method. The oxidation-resistant heat-resistant alloy of the present disclosure, by mass percentage, includes: 2.5%-6% of Al, 24%-30% of Cr, 0.3%-0.55% of C, 30%-50% of Ni, 2%-8% of W, 0.01%-0.2% of Ti, 0.01%-0.2% of Zr, 0.01%-0.4% of Hf, 0.01%-0.2% of Y, 0.01%-0.2% of V, N<0.05%, 0<0.003%, S<0.003%, and Si<0.5%, the balance being Fe and inevitable impurities; wherein merely one of Ti and V is comprised. The method for preparing the oxidation-resistant heat-resistant alloy includes: smelting with inactive element materials.fwdarw.refining.fwdarw.adding mixed rare earth.fwdarw.adding slag.fwdarw.alloying active elements.