This steel sheet has a base steel sheet, a coated portion, and an exposed portion, the shape of the end edge side of the steel sheet and the end portion on the outer side of the base steel sheet is a protruded curve represented by a curvature radius R1 and R1 is 5 μm or more.

An apparatus, material and method for forming a brazing sheet has a high strength core bonded with corrosion protection layer on the coolant side and/or layers on both airside and coolant side. The material enables heat exchanger components, such as tube, header, plate, etc., for applications, such as automotive heat exchangers, that require high fatigue life as well as high service life in a corrosive environment.

Disclosed is a clad steel plate with further improved low temperature toughness along with excellent HIC resistance while ensuring a tensile strength of 535 MPa or more. A clad steel plate includes: a base steel; and a clad metal made of a corrosion resistant alloy bonded to one surface of the base steel, in which the base steel has: a chemical composition with appropriately controlled values of ACR and P.sub.HIC; and a steel microstructure in which bainite is present in an area fraction of 94% or more at a ½ thickness position in a thickness direction of the base steel, and with an average crystal grain size of 25 μm or less, and shear strength at a bonded interface between the base steel and the cladding metal is 300 MPa or more.

Provided is a low-density clad steel sheet having excellent formability and fatigue properties, including a base material; and cladding materials provided on both side surfaces of the base material, wherein the base material is a lightweight steel sheet including, by weight, C: 0.3 to 1.0%, Mn: 4.0 to 16.0%, Al: 4.5 to 9.0%, and a remainder of Fe and inevitable impurities, and each of the cladding materials is martensitic carbon steel including, by weight, C: 0.1 to 0.45%, Mn: 1.0 to 3.0%, and a remainder of Fe and inevitable impurities.

The invention relates to a ballistic steel or wear-resistant steel (1) made up of a multilayer steel materials composite comprising a first layer (1.1) composed of a steel which in the hardened or tempered state has a hardness of >350 HBW and at least one second layer (1.2) which is composed of a steel which is softer compared to the first layer (1.1) and is joined by substance-to-substance bonding to the first layer (1.1), wherein the second layer (1.2) has a hardness which is at least 20% lower than that of the first layer (1.1) in the hardened or tempered state. The invention further relates to a corresponding use of the ballistic steel or wear-resistant steel (1).

A component made of metallic composite material having high corrosion resistance and scale resistance. The metallic composite material contains as a core material an uncoated hardenable steel on which surface a corrosion resistance and scaling resistance layer is provided using heat resistant stainless steel, and has a yield strength Rp.sub.0,2 of at least 1000 MPa and a tensile strength R.sub.m of at least 1500 MPa for the core material and a critical scaling resistance temperature in air for the layer material is at least 850° C.

A clad material includes a first layer made of stainless steel and a second layer made of Cu or a Cu alloy and roll-bonded to the first layer. In the clad material, a grain size of the second layer measured by a comparison method of JIS H 0501 is 0.150 mm or less.

Provided is an alloyed galvanized steel sheet with excellent resistance to cracking in resistance welding at a welded portion, even if crystal orientations of an Fe-based electroplating layer and a cold-rolled steel sheet are integrated at a high ratio at the interface between the Fe-based electroplating layer and the cold-rolled steel sheet. The alloyed galvanized steel sheet has a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % to 3.0 mass %; an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet with a coating weight per surface exceeding 20.0 g/m.sup.2, and an alloyed galvanized layer formed on the Fe-based electroplating layer, where crystal orientations of the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet are integrated at a ratio of more than 50% at the interface between the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet.

Provided is a galvanized steel sheet with excellent resistance to cracking in resistance welding at a welded portion, even if crystal orientations of an Fe-based electroplating layer and a cold-rolled steel sheet are integrated at a high ratio at the interface between the Fe-based electroplating layer and the cold-rolled steel sheet. The galvanized steel sheet has a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % to 3.0 mass %; an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet with a coating weight per surface of more than 20.0 g/m.sup.2, and a galvanized layer formed on the Fe-based electroplating layer, where crystal orientations of the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet are integrated at a ratio of more than 50 % at the interface between the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet.

A surface-treated steel sheet includes a steel sheet, and an NiCoFe alloy layer containing Ni, Co, and Fe on the steel sheet surface. In the thickness direction of the NiCoFe alloy layer, a Co concentration in the NiCoFe alloy layer is highest at a position which is on an outermost surface side of the NiCoFe alloy layer relative to a position where the Ni concentration is highest in the NiCoFe alloy layer, and which is between the outermost surface of the NiCoFe alloy layer and a depth of 100 nm from the outermost surface. In the NiCoFe alloy layer, an Ni-concentrated region in which the Ni concentration increases toward the outermost surface of the NiCoFe alloy layer is formed between the outermost surface of the NiCoFe alloy layer and the position where the Co concentration is highest.