A hot dip method of forming an Al—Zn—Si—Mg alloy coating on a strip is disclosed. The method includes control-ling the conditions in the molten bath to minimise the top dross layer in the molten bath. In particular, the method includes con-trolling top dross formation by including Ca and/or Sr in the coating alloy in the bath.

A method for producing a cold rolled steel sheet having a tensile strength≥1470 MPa and a total elongation TE≥19%, the method comprising the steps of annealing at an annealing temperature AT≥Ac3 a non-treated steel sheet whose chemical composition contains in weight %: 0.34%≤C≤0.40%, 1.50%≤Mn≤2.30%, 1.50≤Si≤2.40%, 0%<Cr≤0.5%, 0%<Mo≤0.3%, 0.01%≤Al≤0.07%, the remainder being Fe and unavoidable impurities, quenching the annealed steel sheet by cooling it to a quenching temperature QT<Ms transformation point and between 150° C. and 250° C., and making a partitioning treatment by reheating the quenched steel sheet to a partitioning temperature PT between 350° C. and 420° C. and maintaining the steel sheet at this temperature during a partitioning time Pt between 15 seconds and 120 seconds.

A method for producing a cold rolled steel sheet having a tensile strength≥1470 MPa and a total elongation TE≥19%, the method comprising the steps of annealing at an annealing temperature AT≥Ac3 a non-treated steel sheet whose chemical composition contains in weight %: 0.34%≤C≤0.40%, 1.50%≤Mn≤2.30%, 1.50≤Si≤2.40%, 0%<Cr≤0.5%, 0%<Mo≤0.3%, 0.01%≤Al≤0.07%, the remainder being Fe and unavoidable impurities, quenching the annealed steel sheet by cooling it to a quenching temperature QT<Ms transformation point and between 150° C. and 250° C., and making a partitioning treatment by reheating the quenched steel sheet to a partitioning temperature PT between 350° C. and 420° C. and maintaining the steel sheet at this temperature during a partitioning time Pt between 15 seconds and 120 seconds.

A method for producing a cold rolled steel sheet having a tensile strength ≥1470 MPa and a total elongation TE≥19%, the method comprising the steps of annealing at an annealing temperature AT≥Ac3 a non-treated steel sheet whose chemical composition contains in weight %: 0.34%≤C≤0.40%, 1.50%≤Mn≤2.30%, 1.50≤Si≤2.40%, 0<Cr≤0.5%, 0<Mo≤0.3%, 0.01%≤Al≤0.07%, the remainder being Fe and unavoidable impurities, quenching the annealed steel sheet by cooling it to a quenching temperature QT<Ms transformation point and between 150° C. and 250° C., and making a partitioning treatment by reheating the quenched steel sheet to a partitioning temperature PT between 350° C. and 420° C. and maintaining the steel sheet at this temperature during a partitioning time Pt between 15 seconds and 120 seconds.

A method for producing a cold rolled steel sheet having a tensile strength ≥1470 MPa and a total elongation TE≥19%, the method comprising the steps of annealing at an annealing temperature AT≥Ac3 a non-treated steel sheet whose chemical composition contains in weight %: 0.34%≤C≤0.40%, 1.50%≤Mn≤2.30%, 1.50≤Si≤2.40%, 0<Cr≤0.5%, 0<Mo≤0.3%, 0.01%≤Al≤0.07%, the remainder being Fe and unavoidable impurities, quenching the annealed steel sheet by cooling it to a quenching temperature QT<Ms transformation point and between 150° C. and 250° C., and making a partitioning treatment by reheating the quenched steel sheet to a partitioning temperature PT between 350° C. and 420° C. and maintaining the steel sheet at this temperature during a partitioning time Pt between 15 seconds and 120 seconds.

The galvanized member includes a member formed of a metal and a hot-dip galvanized layer formed on the surface of the member. The hot-dip galvanized layer contains a sulfate salt having a higher water solubility than calcium sulfate. A sulfate salt content of the hot-dip galvanized layer is preferably 0.008 to 0.133 mol based on 100 g of zinc. The sulfate salt contained in the hot-dip galvanized layer is preferably at least one of potassium sulfate, sodium sulfate, magnesium sulfate, calcium sulfate, ferric sulfate, ferrous sulfate, lithium sulfate, calcium sulfate, and aluminum sulfate.

The galvanized member includes a member formed of a metal and a hot-dip galvanized layer formed on the surface of the member. The hot-dip galvanized layer contains a sulfate salt having a higher water solubility than calcium sulfate. A sulfate salt content of the hot-dip galvanized layer is preferably 0.008 to 0.133 mol based on 100 g of zinc. The sulfate salt contained in the hot-dip galvanized layer is preferably at least one of potassium sulfate, sodium sulfate, magnesium sulfate, calcium sulfate, ferric sulfate, ferrous sulfate, lithium sulfate, calcium sulfate, and aluminum sulfate.

The present invention discloses a durable super-hydrophobic manganese dioxide coating and a preparation method thereof, belonging to the field of metallic material surface treatment. In the method, by using manganese sulfate as a raw material, based on the property of interface reaction, a manganese dioxide coating is synthesized on the metallic material surface by simple and convenient solution impregnation, and then processed by hydrophobization with stearic acid to obtain a super-hydrophobic manganese dioxide coating. This coating has excellent chemical stability to organic solvents such as n-hexane, isooctane, dodecane, tetradecane, and acids, alkali and salt solutions at different pH values, and exhibits great resistance against dynamic water shear and good durability, with broad application prospect.

The present invention discloses a durable super-hydrophobic manganese dioxide coating and a preparation method thereof, belonging to the field of metallic material surface treatment. In the method, by using manganese sulfate as a raw material, based on the property of interface reaction, a manganese dioxide coating is synthesized on the metallic material surface by simple and convenient solution impregnation, and then processed by hydrophobization with stearic acid to obtain a super-hydrophobic manganese dioxide coating. This coating has excellent chemical stability to organic solvents such as n-hexane, isooctane, dodecane, tetradecane, and acids, alkali and salt solutions at different pH values, and exhibits great resistance against dynamic water shear and good durability, with broad application prospect.

A method IS for producing a cold rolled steel sheet having a tensile strength ≥1470 MPa and a total elongation TE≥19%. The method includes the steps of annealing at an annealing temperature AT≥Ac3 a non-treated steel sheet whose chemical composition contains in weight %: 0.34%≤C≤0.40%, 1.50%≤Mn≤2.30%, 1.50≤Si≤2.40%, 0%<Cr≤0.7%, 0%≤Mo≤0.3%, 0.01%≤Al≤0.07%, the remainder being Fe and unavoidable impurities, quenching the annealed steel sheet by cooling it to a quenching temperature QT<Ms transformation point and between 150° C. and 250° C., and making a partitioning treatment by reheating the quenched steel sheet to a partitioning temperature PT between 350° C. and 420° C. and maintaining the steel sheet at this temperature during a partitioning time Pt between 15 seconds and 250 seconds.