An installation for coating a longitudinally-running, strip-shaped metal product includes a tank containing a coating in liquid form, into which the metal product is dipped, a wiping system disposed at a vertical outlet of the product from the tank and intended to wipe each face of the strip-shaped product, at least one ancillary device disposed at an outlet of the product from the wiping system in a manner facing one of the faces of the product, and a holding device holding the wiping system and the ancillary device. The holding device includes a securing unit forming a common lateral support for the wiping system and each ancillary device by using multiple securing points.

An installation for coating a longitudinally-running, strip-shaped metal product includes a tank containing a coating in liquid form, into which the metal product is dipped, a wiping system disposed at a vertical outlet of the product from the tank and intended to wipe each face of the strip-shaped product, at least one ancillary device disposed at an outlet of the product from the wiping system in a manner facing one of the faces of the product, and a holding device holding the wiping system and the ancillary device. The holding device includes a securing unit forming a common lateral support for the wiping system and each ancillary device by using multiple securing points.

A hot-dipped galvanized steel sheet of the present invention includes: a base steel sheet; a ZnMgAl based plating layer provided on at least one surface of the base steel sheet and including, in wt %, with respect to components other than iron (Fe) diffused from the base steel sheet, 5.1 to 25% of Al and 4.0-10% of Mg, and the remainder of Zn and other inevitable impurities; and an interfacial alloy layer having a FeAlZn composition formed between the base steel sheet and the plating layer, wherein the interfacial alloy layer has a thickness of 0.5-2 m and has a dendritic form, the ZnMgAl based plating layer has a ZnAlMgZn.sub.2 ternary eutectic structure, a ZnMgZn.sub.2 binary eutectic structure, and a structure including one or more of an Al single-phase structure having solid-solubilized Zn and a Zn single-phase structure, and agglomerated Al is included in a MgZn.sub.2 structure.

A hot-dipped galvanized steel sheet of the present invention includes: a base steel sheet; a ZnMgAl based plating layer provided on at least one surface of the base steel sheet and including, in wt %, with respect to components other than iron (Fe) diffused from the base steel sheet, 5.1 to 25% of Al and 4.0-10% of Mg, and the remainder of Zn and other inevitable impurities; and an interfacial alloy layer having a FeAlZn composition formed between the base steel sheet and the plating layer, wherein the interfacial alloy layer has a thickness of 0.5-2 m and has a dendritic form, the ZnMgAl based plating layer has a ZnAlMgZn.sub.2 ternary eutectic structure, a ZnMgZn.sub.2 binary eutectic structure, and a structure including one or more of an Al single-phase structure having solid-solubilized Zn and a Zn single-phase structure, and agglomerated Al is included in a MgZn.sub.2 structure.

Disclosed in the present invention are a 800 MPa-grade high-hole-expansion hot-dip galvanized steel plate and a manufacturing method therefor. The steel plate comprises a substrate and a hot-dip galvanizing layer plated on at least one surface of the substrate, wherein the substrate contains Fe and inevitable impurity elements, and further contains the following chemical elements in percentage by mass: 0.03-0.08% of C, 0<Si0.45%, 1.3-1.8% of Mn, 0.02-0.1% of Al, 0.2-0.6% of Cr, 0.05-0.15% of Ti, Nb0.05%, and B0.003%, and the mass percentage contents of N, Ti and Nb also satisfying 0.01%(Ti-3.43N+0.52Nb)/40.03%. The 800 MPa-grade high-hole-expansion hot-dip galvanized steel plate has very excellent mechanical properties, longitudinal yield strength thereof being 660 MPa, tensile strength thereof being 780 MPa, an elongation percentage A50 thereof being 15%, a punching hole-expansion rate thereof being 50% and a reaming hole-expansion rate being 80%.

Disclosed in the present invention are a 800 MPa-grade high-hole-expansion hot-dip galvanized steel plate and a manufacturing method therefor. The steel plate comprises a substrate and a hot-dip galvanizing layer plated on at least one surface of the substrate, wherein the substrate contains Fe and inevitable impurity elements, and further contains the following chemical elements in percentage by mass: 0.03-0.08% of C, 0<Si0.45%, 1.3-1.8% of Mn, 0.02-0.1% of Al, 0.2-0.6% of Cr, 0.05-0.15% of Ti, Nb0.05%, and B0.003%, and the mass percentage contents of N, Ti and Nb also satisfying 0.01%(Ti-3.43N+0.52Nb)/40.03%. The 800 MPa-grade high-hole-expansion hot-dip galvanized steel plate has very excellent mechanical properties, longitudinal yield strength thereof being 660 MPa, tensile strength thereof being 780 MPa, an elongation percentage A50 thereof being 15%, a punching hole-expansion rate thereof being 50% and a reaming hole-expansion rate being 80%.