Abstract: An aqueous treating solution for an Sn-based plated steel sheet, comprising (A) an organic material, (B) a water-soluble chromium compound, (C) a water-dispersible silica, and water, wherein the organic material (A) is at least one member selected from an oxy-acid with the ratio of hydroxyl group/carboxyl group in one molecule being from 3/1 to 10/1, its lactone form and an oxide derivative thereof, the water-soluble chromium compound (B) does not contain hexavalent chromium, and pH is from 0.7 to 6.0.

Abstract: An exemplary embodiment of manufacturing a hot-dip Sn—Zn coated steel sheet is provided which can include pre-coating a Fe—Ni alloy containing between about 10 to 80 mass % of Ni, and a remainder being Fe on a steel sheet, immersing the steel sheet into a Sn—Zn hot-dip coating bath so as to form a hot-dip coating layer on the steel sheet, cooling the hot-dip coating layer at a cooling rate of about 10° C./sec to about 30° C./sec so as to obtain a hot-dip Sn—Zn coated steel sheet, measuring a differential scanning calorimetric curve of the hot-dip Sn—Zn coated steel sheet by a differential scanning calorimetry, and distinguishing whether the hot-dip Sn—Zn coated steel sheet has an objective microstructure by the measured differential scanning calorimetric curve.

Abstract: An aqueous treating solution for an Sn-based plated steel sheet, comprising (A) an organic material, (B) a water-soluble chromium compound, (C) a water-dispersible silica, and water, wherein the organic material (A) is at least one member selected from an oxy-acid with the ratio of hydroxyl group/carboxyl group in one molecule being from 3/1 to 10/1, its lactone form and an oxide derivative thereof, the water-soluble chromium compound (B) does not contain hexavalent chromium, and pH is from 0.7 to 6.0.

Abstract: An exemplary embodiment of manufacturing a hot-dip Sn—Zn coated steel sheet is provided which can include pre-coating a Fe—Ni alloy containing between about 10 to 80 mass % of Ni, and a remainder being Fe on a steel sheet, immersing the steel sheet into a Sn—Zn hot-dip coating bath so as to form a hot-dip coating layer on the steel sheet, cooling the hot-dip coating layer at a cooling rate of about 10° C./sec to about 30° C./sec so as to obtain a hot-dip Sn—Zn coated steel sheet, measuring a differential scanning calorimetric curve of the hot-dip Sn—Zn coated steel sheet by a differential scanning calorimetry, and distinguishing whether the hot-dip Sn—Zn coated steel sheet has an objective microstructure by the measured differential scanning calorimetric curve.

Abstract: The present invention provides hot dip plated high strength steel sheet for press forming use having a tensile strength of 380 MPa to less than 540 MPa, having a press formability able to be used for the automobile field, in particular fuel tank applications, and having superior secondary work embrittlement resistance and superior seam weld zone low temperature toughness and further superior plateability and a method of production of the same and provides hot dip plated high strength steel sheet for press forming use of the present invention having cold rolled steel sheet and a hot dip plated layer formed on the surface of said cold rolled steel sheet, characterized in that said cold rolled steel sheet contains, by mass %, C: 0.0005 to 0.0050%, Si: over 0.3 to 1.0%, Mn: 0.70 to 2.0%, P: 0.05% or less, Ti: 0.010 to 0.050%, Nb: 0.010 to 0.040%, B: 0.0005 to 0.0030%, S: 0.010% or less, Al: 0.01 to 0.30%, and N: 0.0010 to 0.

Abstract: An exemplary embodiment of a hot-dip Sn—Zn coated steel sheet is provided which can include a steel sheet and a hot-dip coating layer which is formed on a surface of the steel sheet. The coating layer can contain between about 1 mass % and about 8.8 mass % of Zn, and a remainder including between about 91.2 mass % and about 99.0 mass % of Sn and inevitable impurities. A ratio of an endothermic value of melting heat generated by Sn—Zn eutectic crystals and an endothermic value of melting heat generated by Sn primary crystals in the hot-dip coating layer can satisfy the following relationship: (endothermic value of melting heat generated by Sn primary crystals)/{(endothermic value of melting heat generated by Sn primary crystals)+(endothermic value of melting heat generated by Sn—Zn eutectic crystals)}?about 0.3. Further, a temperature of an endothermic peak generated by melting of the Sn primary crystals can be between about 200° C. and about 230° C.

Abstract: A Pb-free hot-dip Sn—Zn coated steel sheet comprising a hot-dip coating layer comprised of 1 to 8.8 wt % of Zn and the balance of Sn in an amount of 91.2 to 99.0 wt % and unavoidable impurities and/or ancillary ingredients on the surface of steel sheet, the coating surface having Sn dendrite crystals and Sn dendrite arm spacings buried by an Sn—Zn two-way eutectic structure, an area ratio of Sn dendrites in the coating surface being 5 to 90%, and the arm spacing of the Sn dendrites being not more than 0.1 mm, preferably having a discontinuous FeSn2 alloy phase at the surface of the steel sheet.

Abstract: A Pb-free hot-dip Sn—Zn coated steel sheet having superior corrosion resistance and workability and suitable as a material for an automobile fuel tank is provided, that is, hot-dip Sn—Zn coated steel sheet obtained by forming a hot-dip coating layer comprised of 1 to 8.8 wt % of Zn and the balance of Sn in an amount of 91.2 to 99.0 wt % and unavoidable impurities and/or ancillary ingredients on the surface of steel sheet, the coating surface having Sn dendrite crystals and Sn dendrite arm spacings buried by an Sn—Zn two-way eutectic structure, an area ratio of Sn dendrites in the coating surface being 5 to 90%, and the arm spacing of the Sn dendrites being not more than 0.

Abstract: A Sn-based metal-coated steel strip excellent in appearance comprises a Ni-based metal (such as Ni, a Ni—Sn alloy, a Ni—Zn alloy, a Ni—Fe alloy and a Ni—Co alloy) preplating layer and a Sn-based metal (such as a Sn—Zn alloy) coating formed thereon, and is characterized in that a Ni emission intensity line and an Fe emission intensity line obtained by glow discharge spectroscopy of the surface of the coated steel strip satisfy a relationship of the formula: T1?T2 wherein T1 is a sputtering time at the peak of a Ni emission intensity line, and T2 is a sputtering time at the inflection point of an Fe emission intensity line, or a relationship of the formulas: T1?T2, and 1?T1/T2?1.

Abstract: A Sn-based metal-coated steel strip excellent in appearance comprises a Ni-based metal (such as Ni, a Ni-Sn alloy, a Ni-Zn alloy, a Ni-Fe alloy and a Ni-Co alloy) preplating layer and a Sn-based metal (such as a Sn-Zn alloy) coating formed thereon, and is characterized in that a Ni emission intensity line and an Fe emission intensity line obtained by glow discharge spectroscopy of the surface of the coated steel strip satisfy a relationship of the formula: T1≧T2