The present invention relates to a zinc plated steel sheet having excellent surface quality and spot weldability, and a manufacturing method therefore. A zinc plated steel sheet according to one aspect of the present invention comprises a base steel sheet and a zinc-based plating layer formed on the surface of the base steel sheet, wherein the GDOES profile of oxygen, which is measured in the depth direction from the surface of the base steel sheet, has a form in which a local minimum point and a local maximum point alternately appear in the depth direction from the surface, and the difference (a local maximum value—a local minimum value) between the oxygen concentration (a local minimum value) at the local minimum point and the oxygen concentration (a local maximum value) at the local maximum point can be 0.1 wt % or more.

The present invention relates to a zinc plated steel sheet having excellent surface quality and spot weldability, and a manufacturing method therefore. A zinc plated steel sheet according to one aspect of the present invention comprises a base steel sheet and a zinc-based plating layer formed on the surface of the base steel sheet, wherein the GDOES profile of oxygen, which is measured in the depth direction from the surface of the base steel sheet, has a form in which a local minimum point and a local maximum point alternately appear in the depth direction from the surface, and the difference (a local maximum value—a local minimum value) between the oxygen concentration (a local minimum value) at the local minimum point and the oxygen concentration (a local maximum value) at the local maximum point can be 0.1 wt % or more.

A cold-rolled sheet according to an example of the present invention comprises at most 0.004 wt % (exclusive of 0 wt %) of C, at most 0.02 wt % (exclusive of 0 wt %) of Si, 0.1 to 0.3 wt % of Mn, at most 0.05 wt % (exclusive of 0 wt %) of Al, at most 0.02 wt % (exclusive of 0 wt %) of P, at most 0.001 wt % (exclusive of 0 wt %) of S, at most 0.004 wt % (exclusive of 0 wt %) of N, 0.015 to 0.035 wt % of Ti, and 0.001 to 0.003 wt % of B, with the balance being Fe and other inevitable impurities, and has a microstructure in which the crystal grain aspect ratio defined by the following equation 1 is 1.4 to 4.0.

Crystal grain aspect ratio=average crystal grain diameter in the rolling direction/average crystal grain diameter in the thickness direction   [Equation 1]

A cold-rolled sheet according to an example of the present invention comprises at most 0.004 wt % (exclusive of 0 wt %) of C, at most 0.02 wt % (exclusive of 0 wt %) of Si, 0.1 to 0.3 wt % of Mn, at most 0.05 wt % (exclusive of 0 wt %) of Al, at most 0.02 wt % (exclusive of 0 wt %) of P, at most 0.001 wt % (exclusive of 0 wt %) of S, at most 0.004 wt % (exclusive of 0 wt %) of N, 0.015 to 0.035 wt % of Ti, and 0.001 to 0.003 wt % of B, with the balance being Fe and other inevitable impurities, and has a microstructure in which the crystal grain aspect ratio defined by the following equation 1 is 1.4 to 4.0.

Crystal grain aspect ratio=average crystal grain diameter in the rolling direction/average crystal grain diameter in the thickness direction   [Equation 1]

The present disclosure relates to an aluminum alloy-plated steel sheet having excellent workability and corrosion resistance and a method for manufacturing the same, and more particularly, to an aluminum alloy-plated steel sheet preventing microcracks generated during hot forming and has excellent seizure resistance and corrosion resistance, and a method for manufacturing the same.

The present disclosure relates to an aluminum alloy-plated steel sheet having excellent workability and corrosion resistance and a method for manufacturing the same, and more particularly, to an aluminum alloy-plated steel sheet preventing microcracks generated during hot forming and has excellent seizure resistance and corrosion resistance, and a method for manufacturing the same.

The present disclosure relates to a system for manufacturing a hybrid component including a first thermal supplier configured to heat a steel plate, a rolling roll for undercut configured to pressurize the steel plate heated by the first thermal supplier, and to form an undercut on one surface of the steel plate, a first molding roll configured to pressurize the steel plate formed with the undercut to mold the steel plate in a shape of a component to be manufactured, a composite material feeder configured to supply a composite material tape to be seated on one surface of the steel plate formed with the undercut through the first molding roll, and a composite material pressurization roll configured to pressurize the steel plate on which the composite material tape is seated.

A coated steel sheet has a coating film on at least one side of a plated steel sheet. The coating film contains a binder resin, non-oxide ceramic particles containing V (excluding VC particles), and doped zinc oxide particles. The respective contents of the non-oxide ceramic particles containing V and the doped zinc oxide particles relative to the coating film satisfy the expressions: [(1) C.sub.Zn≥10.0, (2) C.sub.V≤0.5.Math.C.sub.Zn, (3) C.sub.V≤70−C.sub.Zn, (4) C.sub.V≥0.125.Math.C.sub.Zn, and (5) C.sub.V≥2.0], where C.sub.V represents the content (mass %) of the non-oxide ceramic particles containing V, and C.sub.Zn represents the content (mass %) of the doped zinc oxide particles. The coated steel sheet is excellent in both corrosion resistance before electrodeposition coating, and weldability.

Provided is a metallic coated steel product which is less likely to experience LME and blowhole formation and is likely to exhibit an improved corrosion resistance at welding heat affected zones. The metallic coated steel product is a hot-dip metallic coated steel product including a steel product and a plating layer that is provided on a surface of the steel product and includes a Zn—Al—Mg alloy layer. In a cross-section of the Zn—Al—Mg alloy layer an area fraction of MgZn.sub.2 phase is from 45 to 75%, a total area fraction of MgZn.sub.2 and Al phases is not less than 70%, and an area fraction of Zn—Al—MgZn.sub.2 ternary eutectic structure is from 0 to 5%; and the plating layer has a predetermined chemical composition.

Provided is a metallic coated steel product which is less likely to experience LME and blowhole formation and is likely to exhibit an improved corrosion resistance at welding heat affected zones. The metallic coated steel product is a hot-dip metallic coated steel product including a steel product and a plating layer that is provided on a surface of the steel product and includes a Zn—Al—Mg alloy layer. In a cross-section of the Zn—Al—Mg alloy layer an area fraction of MgZn.sub.2 phase is from 45 to 75%, a total area fraction of MgZn.sub.2 and Al phases is not less than 70%, and an area fraction of Zn—Al—MgZn.sub.2 ternary eutectic structure is from 0 to 5%; and the plating layer has a predetermined chemical composition.