High strength plated steel sheet having high hydrogen embrittlement resistance, that is, alloyed hot dip galvannealed steel sheet including steel sheet containing C: 0.05 to 0.40%, Si: 0.2 to 3.0%, Mn: 0.1 to 5.0%, and sol. Al: 0.4 to 1.50% and a alloyed hot dip galvannealed layer deposited on at least one surface of the steel sheet to 10 to 100 g/m.sup.2 and containing Fe: 5.0 to 15.0% and Al: 0.01 to 1.0%, having an internal oxidation layer including grain boundary oxides in a surface layer of the steel sheet, when examining a cross-section of a surface layer of the steel sheet, a Ratio A of the length of the grain boundary oxides projected an interface of the steel sheet and the alloyed hot dip galvannealed layer to the length of interface is 50% or more and 100% or less, and a surface depleted layer with a steel composition not including the grain boundary oxides which satisfies, by mass %, Si0.6% and Al0.05% is included at a depth of of the average depth of the internal oxidation layer.

A metal component and an electronic device including a metal component is disclosed. In one example, the metal component includes a metallic core material, a first metal layer arranged over the metallic core material, a second metal layer arranged over the first metal layer, and an intermetallic compound layer. The intermetallic compound layer is arranged between the first metal layer and the second metal layer.

A steel sheet according to an aspect of the present invention has a predetermined chemical composition, in which a metallographic structure in a thickness portion includes, by volume percentage, ferrite: 10% or more and less than 50%, granular bainite: 5% or more and less than 40%, martensite: 30% or more and 55% or less, upper bainite and lower bainite: less than 30% in total, pearlite: less than 10%, and residual austenite: less than 5%, a proportion of the number of the martensites adjacent to the ferrite to the number of the metallographic structures adjacent to the ferrite is 30% or less in the thickness portion, and the difference between the absolute maximum value and the absolute minimum value of Vickers hardness at a load of 50 gf obtained at an interval of 30 m from a position of a depth of 100 m in a sheet thickness direction from a surface of the steel sheet as a starting point to a thickness middle portion position is 60 HV or less.

A hot-dipped galvanized steel sheet of the present invention includes: a base steel sheet; a ZnMgAl based plating layer provided on at least one surface of the base steel sheet and including, in wt %, with respect to components other than iron (Fe) diffused from the base steel sheet, 5.1 to 25% of Al and 4.0-10% of Mg, and the remainder of Zn and other inevitable impurities; and an interfacial alloy layer having a FeAlZn composition formed between the base steel sheet and the plating layer, wherein the interfacial alloy layer has a thickness of 0.5-2 m and has a dendritic form, the ZnMgAl based plating layer has a ZnAlMgZn.sub.2 ternary eutectic structure, a ZnMgZn.sub.2 binary eutectic structure, and a structure including one or more of an Al single-phase structure having solid-solubilized Zn and a Zn single-phase structure, and agglomerated Al is included in a MgZn.sub.2 structure.

Provided is an ultra-high-strength cold-rolled steel sheet with a balanced improvement in strength and ductility, and a method of manufacturing the same. According to an embodiment of the present disclosure, the ultra-high-strength cold-rolled steel sheet includes carbon (C): 0.1 wt % to 0.3 wt %, silicon (Si): 1.0 wt % to 2.0 wt %, manganese (Mn): 1.5 wt % to 3.0 wt %, aluminum (Al): more than 0 wt % and up to 0.05 wt %, a combination of one or more selected from titanium (Ti), niobium (Nb), and vanadium (V): more than 0 wt % and up to 0.05 wt %, phosphorus (P): more than 0 wt % and up to 0.02 wt %, sulfur (S): more than 0 wt % and up to 0.005 wt %, nitrogen (N): more than 0 wt % and up to 0.006 wt %, and a balance of iron (Fe) and other unavoidable impurities, wherein the ultra-high-strength cold-rolled steel sheet meets a yield strength (YS): 850 MPa or more, a tensile strength (TS): 1180 MPa or more, an elongation (EL): 14% or more, a hole expansion ratio (HER): 25% or more, and TSELHER/1000: 500 or more.

This steel sheet has a predetermined chemical composition, and has, at a t/4-position which is a position at a distance of t/4 from the surface in a sheet thickness direction cross section when the sheet thickness is defined as t, a metal structure including 20% or more of ferrite and a total of 40% or more of bainite and martensite in volume fraction, the remaining portion being at least one selected from retained austenite and perlite. In a square-shaped area in which the length of one side is t/4 and which is centered at the t/4-position in the sheet thickness direction cross section, when the Mn concentration is measured at multiple measurement points located apart at a 1 m-interval, the proportion of measurement points in which the Mn concentration is at least 1.1 times of the average value of the Mn concentration at all the measurement points is less than 10.0%. The steel sheet has a tensile strength of 980 MPa or more. The product between the tensile strength and the total elongation of the steel sheet is 10500 MPa.Math.% or more.

This cold-rolled steel sheet has a predetermined chemical composition, in which a metallographic structure of a t/4 portion, which is at a position of a sheet thickness t from a surface of the cold-rolled steel sheet in a sheet thickness direction, includes, by volume percentage, retained austenite: 2.5% or more and 10.0% or less, tempered martensite: 80.0% or more and 97.5% or less, ferrite and bainite: 0.0% or more and 15.0% or less in total, and martensite: 0.0% or more and 3.0% or less, and in a surface layer area at a position 25 m away from the surface in the sheet thickness direction, an amount of solute Si is 0.30% or more and 1.50% or less by mass %, a volume percentage of ferrite in the metallographic structure is 0.0% or more and 20.0% or less, and a density of ferrite grains having a grain size of 15 m or more is 0 grains/mm.sup.2 or more and 3,000 grains/mm.sup.2 or less.

To provide a galvanized steel sheet having high strength; specifically, with a tensile strength of 1160 MPa or more and excellent resistance spot weldability. A chemical composition of a base steel sheet contains one or more of Ti, Nb, V, and Zr: 0.02% or more and 0.20% or less in total, and an amount of diffusible hydrogen in a zinc or zinc alloy coating layer is 0.40 mass ppm or less.

The present invention provides a 100 kg-grade ultra-high-strength galvanized steel sheet having excellent resistance spot welding properties and excellent resistance to liquid metal embrittlement (LME) cracking. The steel sheet contains the following components in percentage by weight: C: 0.17-0.25%, Mn: 1.7-2.7%, Si: 0.35-1.5%, Al: 0.01-1.0%, 0.7%Si+Al1.7%, and at least one of Nb, Ti and B, with the balance being Fe and unavoidable impurities. When the thickness of the steel sheet is t, the resistivity thereof is 0<R.sub.150 .Math.cm; and, in the direction from the coating layer/steel sheet substrate interface to the steel sheet substrate, when the thickness of the steel sheet is in the range of greater than or equal to 0.010t to less than or equal to 0.035t the resistivity thereof is 0<R.sub.215 .Math.cm, and when the thickness of the steel sheet is in the range of greater than 0.035t to less than or equal to 0.065t the resistivity thereof is 0<R.sub.330 .Math.cm, wherein (R.sub.2/2+R.sub.3/3)(3.1R.sub.1.sup.1/21.5) is satisfied.

An objective of the present invention is to provide a steel sheet having a high strength which can provide excellent appearance quality. The steel sheet has a chemical composition including, in mass %, C: more than 0.030% to 0.145%, Si: 0% to 0.500%, Mn: 0.50% to 2.50%, P: 0% to 0.100%, S: 0% to 0.020%, Al: 0% to 1.000% or less, N: 0% to 0.0100%, and the like, wherein a metal micro-structures consisting of 70 to 95% of ferrite in volume fraction and 5 to 30% of hard phases in volume fraction, and a value X1 obtained by dividing a standard deviation of average Mn concentrations in a rolling direction at sheet-thickness positions in a sheet thickness direction by an average Mn concentration at the sheet-thickness positions is 0.025 or less.