Provided is a hot-dip galvanized steel sheet including a base steel sheet and a hot-dip zinc-based plating layer formed on the base steel sheet. The hot-dip zinc-based plating layer includes a Zn single phase having an average equivalent circular diameter of 120 μm or less as a microstructure. In the Zn single phase, a Zn single phase having a crystal structure of which a {0001} plane is parallel to a surface of the steel sheet, is provided in an area fraction of 70% or less.

A high-strength hot-dip coated hot-rolled steel sheet excellent in terms of surface appearance quality and coating adhesiveness and a method for manufacturing. The method includes performing hot rolling followed by pickling on steel to form a pickled steel sheet, the steel having a chemical composition containing, by mass %, C: 0.02% or more and 0.30% or less, Si: 0.01% or more and 1.0% or less, Mn: 0.3% or more and 2.5% or less, P: 0.08% or less, S: 0.02% or less, Al: 0.001% or more and 0.20% or less, and Fe and inevitable impurities. The method further includes performing rolling with a rolling reduction ratio of 1% or more and 10% or less, and a hot-dip coating treatment. The obtained steel sheet has an arithmetic average roughness Ra of 2.0 μm or less on the surface of the steel sheet, and a tensile strength of 590 MPa or more.

A method for producing a cold rolled and hot dip coated steel sheet is provided. The method includes casting a steel into a slab, reheating, hot rolling, cooling, coiling, descaling and cold rolling the slab. The cold rolled steel sheet is annealed so a layer of iron oxide forms on the surface with an internal oxidation underneath. The sheet is then heated so the surface is oxidized and the layer of iron oxide is fully reduced to obtain an internally oxidized depth between 200 nm and 100 μm which includes one or more of Si, Mn, Al, Ti containing oxides. The sheet is then hot dip coated and cooled.

A hot-dip galvanized steel sheet includes a plated layer formed on at least a part of a surface of a steel sheet, the plated layer containing: Al in a range from 10 mass % to 40 mass %; Si in a range from 0.05 mass % to 4 mass %; Mg in a range from 0.5 mass % to 4 mass %; and the balance consisting of Zn and inevitable impurities. The plated layer has a lamellar structure in which a layered Zn phase and a layered Al phase are alternately arranged in a cross section of the plated layer, the lamellar structure accounting for 5% or more by an area fraction in the cross section, and a total abundance ratio of an intermetallic compound containing at least one of Fe, Mn, Ti, Sn, In, Bi, Pb or B is regulated to 3% or less by the area fraction.

Provided is a method of manufacturing a hot-dip galvanized steel sheet. According to an aspect of the present invention, the method may include preparing a base steel sheet, forming a iron (Fe)-plated layer on the prepared base steel sheet, oxidation heating the steel sheet having the Fe-plated layer formed thereon at a temperature ranging from 600° C. to 800° C., maintaining the heated steel sheet at a temperature ranging from 750° C. to 900° C. for 5 seconds or more in a reducing atmosphere with a dew point of between −30° C. to 5° C. including 20 ppm or less of oxygen, 1 vol % to 20 vol % of H.sub.2, and N.sub.2 as well as unavoidable gases as a remainder, cooling the maintained steel sheet, and plating the cooled steel sheet by dipping in a hot-dip galvanizing bath.

A method for producing a steel strip containing, in addition to iron as the main component and unavoidable impurities, one or more of the following oxygen-affine elements in wt. %: Al: more than 0.02, Cr: more than 0.1, Mn: more than 1.3 or Si: more than 0.1, where the surface of the steel strip is cleaned, oxidation-treated and annealed. The treated and annealed steel strip is subsequently coated with a hot-dip coat. In order to be less cost-intensive and to achieve uniform, reproducible adhesion conditions for the coat, the steel strip is oxidation-treated prior to the annealing at temperatures below 200° C., where on the surface of the steel strip, with the formation of oxides with iron from the steel strip, an oxide layer is formed, which contains iron oxide and is reduction-treated during the course of the annealing under a reducing atmosphere to achieve a surface consisting substantially of metallic iron.

An aluminum-based plated steel sheet according to an aspect of the present invention includes: a base material; an aluminum-based plating layer located above the base material; and an intermetallic compound layer that is located between the base material and the aluminum-based plating layer and contains an intermetallic compound of Al and Fe, in which the base material has a chemical component within a predetermined range, the aluminum-based plating layer contains, on average, 80 mass % or more and 97 mass % or less of Al, 3 mass % or more and 15 mass % or less of Si, 0 mass % or more and 5 mass % or less of Zn, 0 mass % or more and 5 mass % or less of Fe, 0 mass % or more and 3 mass % or less in total of one or more selected from the group consisting of Mg and Ca, and impurities so that a total amount thereof is 100 mass %, an average value of a thickness of the intermetallic compound layer is 2 μm or more and 10 μm or less, a maximum value of the thickness of the intermetallic compound layer is 10 μm or more and 25 μm or less, and a standard deviation of the thickness of the intermetallic compound layer is 2 μm or more and 10 μm or less.

A method for producing a high-strength galvanized steel sheet having excellent fatigue resistance properties. The method includes an oxidation processing in which a steel sheet is heated at a temperature of 400 to 750° C. in an atmosphere having an O.sub.2 concentration of 1000 ppm by volume or more and a H.sub.2O concentration of 1000 ppm by volume or more, and the steel sheet is heated at a temperature of 600 to 850° C. in an atmosphere having an O.sub.2 concentration of less than 1000 ppm by volume and a H.sub.2O concentration of 1000 ppm by volume or more. The method also includes reduction-annealing in which the steel sheet is heated at a heating rate of 0.1° C./sec or more to a temperature of 650 to 900° C. in an atmosphere having a H.sub.2 concentration of 5 to 30 vol % and a H.sub.2O concentration of 10 to 1000 ppm by volume.

The present disclosure relates to a zinc-based alloy coating for steel strip through a continuous galvanizing process. This zinc-based alloy coating provides the steel with cathodic protection before and after the steel is press hardened processing at a high austenitization temperature up to 950° C. The zinc-based alloy coating also reduces or eliminates the susceptibility to liquid metal embrittlement during or after welding for various types of non-press hardenable advanced ultra high-strength steels. The zinc-based alloy comprises at least one element selected from manganese (Mn) and/or antimony (Sb).

A method and arrangement for manufacturing hot dip galvanized rolled high strength steel product is presented. The method comprises providing a rolled steel product, heating and annealing the rolled steel product for creating a layer of iron oxide on the surface of the rolled steel product, cooling the rolled steel product, having the iron oxide layer, in a first cooling step to a temperature in a temperature range of 560-600° C. and holding for 3-10 seconds, quenching said rolled steel product, covered with the layer of iron oxide, in a second cooling step by immersing it into a zinc bath comprising aluminium and having a temperature between 440-450° C. for 1-5 seconds and cooling the rolled steel product in a third cooling step to room temperature. An arrangement for implementing the method is also presented.