A method for manufacturing a high-strength galvanized steel sheet having excellent strength-elongation balance, coating adhesiveness, and surface appearance. The method includes: (i) a first heating process of heating a steel sheet having a predetermined chemical composition, (ii) a first pickling process of pickling the steel sheet which was subjected to the first heating process in an oxidizing acidic aqueous solution, (iii) a second pickling process of pickling the steel sheet which was subjected to the first pickling process in a non-oxidizing acidic aqueous solution, (iv) a second heating process of holding the steel sheet, which was subjected to the second pickling process, at a temperature range of 700 C. or higher and 900 C. or lower in a hydrogen-containing atmosphere for 20 seconds or more and 300 seconds or less, and (v) performing a galvanizing treatment on the steel sheet which was subjected to the second heating process.

Disclosed is a high-strength steel sheet having a tensile strength (TS) of 780 MPa or more and excellent in ductility, fatigue properties, stretch flangeability, surface characteristics, and sheet passage ability that can be obtained by providing a predetermined chemical composition and a steel microstructure that contains, by area, 20-50% of ferrite, 5-25% of bainitic ferrite, 1-10% of martensite, and 5-15% of tempered martensite, and that contains, by volume, 10% or more of retained austenite, in which the retained austenite has a mean grain size of 2 m or less, a mean Mn content in the retained austenite in mass % is at least 1.2 times the Mn content in the steel sheet in mass %, the retained austenite has a mean free path of 1.2 m or less, and the tempered martensite has a mean free path of 1.2 m or less.

Disclosed is a high-strength steel sheet having a tensile strength (TS) of 780 MPa or more and excellent in ductility, fatigue properties, stretch flangeability, surface characteristics, and sheet passage ability that can be obtained by providing a predetermined chemical composition and a steel microstructure that contains, by area, 20-50% of ferrite, 5-25% of bainitic ferrite, 1-10% of martensite, and 5-15% of tempered martensite, and that contains, by volume, 10% or more of retained austenite, in which the retained austenite has a mean grain size of 2 m or less, a mean Mn content in the retained austenite in mass % is at least 1.2 times the Mn content in the steel sheet in mass %, the retained austenite has a mean free path of 1.2 m or less, and the tempered martensite has a mean free path of 1.2 m or less.

A plant for cleaning rolled metal strips provided with a superficial layer of oxide, the plant comprising unwinding means for unwinding at least one coil of rolled strip and pickling means for pickling said rolled strip; wherein there are provided measuring means for measuring the thickness of the superficial layer of oxide, arranged between said unwinding means and said pickling means. A relating cleaning method is also claimed.

An approach to provide an electronic assembly process that includes receiving at least one electronic assembly after a solder reflow process using a Sn-containing solder and a water-soluble flux. The approach includes baking the at least one electronic assembly in an oxygen containing environment and, then cleaning the at least one electronic assembly in an aqueous cleaning process.

An approach to provide an electronic assembly process that includes receiving at least one electronic assembly after a solder reflow process using a Sn-containing solder and a water-soluble flux. The approach includes baking the at least one electronic assembly in an oxygen containing environment and, then cleaning the at least one electronic assembly in an aqueous cleaning process.

An aluminum alloy is described and has compositions with mass percentage content consisting of: 5.0%-5.4% Zn; 0.9%-1.2% Mg; Cu<0.05%; Si<0.05%; Fe<0.1%; Mn<0.05%; Zr<0.1%; Ti<0.05%; other impurities <0.15%; and the remaining composition being Al. An anodizing method of the aluminum alloy described above is described and has: a degreasing treatment, a first black-film stripping treatment, a chemical polishing treatment, a second black-film stripping treatment, an anodizing treatment, a hole filling treatment and a drying treatment which are performed in turn. The aluminum alloy has a higher strength while eliminating an influence of a formed compound phase on a material texture.

The present invention provides a cold-rolled and annealed steel sheet with a strength greater than 1200 MPa, the composition of which includes, the contents being expressed by weight: 0.10%C0.25%, 1%Mn3%, A0.010%, Si2.990%, S0.015%, P0.1%, N0.008%, it being understood that 1%Si+Al3%, it being understood that Cr+3Mo0.3%, Ti in an amount such that Ti/N4 and Ti0.040%. A balance of the composition includes iron and inevitable impurities resulting from the smelting. The microstructure of the steel includes 15 to 90% bainite, the remainder includes martensite and residual austenite.

The present invention provides a cold-rolled and annealed steel sheet with a strength greater than 1200 MPa, the composition of which includes, the contents being expressed by weight: 0.10%C0.25%, 1%Mn3%, A0.010%, Si2.990%, S0.015%, P0.1%, N0.008%, it being understood that 1%Si+Al3%, it being understood that Cr+3Mo0.3%, Ti in an amount such that Ti/N4 and Ti0.040%. A balance of the composition includes iron and inevitable impurities resulting from the smelting. The microstructure of the steel includes 15 to 90% bainite, the remainder includes martensite and residual austenite.

A high-strength cold-rolled steel sheet has a composition that contains, in terms of mass %, C: 0.10% or more and 0.50% or less, Si: 1.0% or more and 3.0% or less, Mn: 1.0% or more and 2.5% or less, P: 0.05% or less, S: 0.02% or less, Al: 0.01% or more and 1.5% or less, N: 0.005% or less, Cu: 0.05% or more and 0.50% or less, and the balance being Fe and unavoidable impurities, wherein a proportion of a steel sheet surface covered with oxides mainly composed of Si is 1% or less, a proportion of the steel sheet surface covered with Fe oxides is 40% or less, Cu.sub.S/Cu.sub.B is 4.0 or less, and a tensile strength is 1180 MPa or more, when Cu.sub.S denotes the Cu content in a steel sheet surface layer and Cu.sub.B denotes the Cu content in a base material.