A correction apparatus for correcting the planarity of a metal strip advancing into a coating system for coating said metal strip with a layer of molten metal, said apparatus comprising

a bridle roll, which modifies the feeding direction of the metal strip exiting an annealing furnace;

only one sink roll, arranged downstream of said bridle roll and inside a tank adapted to contain a bath of said molten metal;

a correction device for correcting the planarity of the metal strip arranged between said bridle roll and said sink roll;

wherein said correction device comprises at least two motorized rolls;

wherein a first motorized roll of said at least two motorized rolls is distal from said bridle roll in a fixed position with respect to a feeding path of the metal strip, said first motorized roll being arranged on a first side of said feeding path;

wherein said bridle roll is also arranged on said first side;

and wherein a second motorized roll of said at least two motorized rolls is proximal to said bridle roll and movable along the direction of the strip thickness, said second motorized roll being arranged on a second side, opposite to the first side, of said feeding path.

A gas wiping nozzle configured to blow wiping gas onto a metal strip includes a first nozzle member and a second nozzle member provided to face each other, in which a slit as a gas blowing port is formed to extend in a length direction between end portions of the first nozzle member and the second nozzle member on the metal strip side; and a shim member configured to adjust a gap of the slit in a width direction orthogonal to the length direction, wherein the shim member is made of a ceramic material or a carbon material, each of the first nozzle member and the second nozzle member has a groove portion, and the shim member is fitted into both of the groove portions of the first nozzle member and the second nozzle member and fixes the first nozzle member and the second nozzle member.

A method for producing a hot-dip galvanized steel sheet includes supplying humidified gas to the soaking zone 12 in a manner such that: in passes in which the steel sheet moves upward, the humidified gas is supplied from first humidified gas supply ports 40A to 40E provided at positions higher by 1.0 m or more and 5.0 m or less than the centers of lower hearth rolls 54 and overlapping the steel sheet in the passes when viewed from the side of the soaking zone; and in passes in which the steel sheet moves downward, the humidified gas is supplied from second humidified gas supply ports 42A to 42E provided at positions lower by 1.0 m or more and 5.0 m or less than the centers of the upper hearth rolls 52 and overlapping the steel sheet in the passes when viewed from the side of the soaking zone.

The present invention relates to an apparatus and a method of manufacturing a hot dipped galvanized steel sheet that is excellent in corrosion resistance and has no linear defects, thereby being available for automobile bodies, household appliances, construction materials, and the like which need aesthetic surfaces. The apparatus for manufacturing a hot dipped galvanized steel sheet includes: a plating pot filled with a galvanizing bath for coating of a steel sheet; a sink roll; a wiping device adjusting the thickness of the coating on the steel sheet; a top roll; an oxidation process chamber; and an air cooling device. According to the present invention, after an excess molten coating solution attached to the steel sheet is evenly removed, an oxide film is made to be 0.1 μm to 0.3 μm thick before a coating layer starts to solidify. Thus, linear defects can be prevented.

A method for monitoring a manufacturing of a metal product, the metal product being manufactured according to a manufacturing process, is implemented by an electronic monitoring device. This method includes acquiring (100) a measured value of at least one representative parameter, each representative parameter being a parameter relating to the metal product or a parameter relating to the manufacturing process, determining (130) a status of the metal product among a compliant status and an analysis status, depending on the at least one acquired value and on at least one target, and when the determined status is the analysis status, computing (150) a corrective action to be applied to the product, among a set of corrective actions and depending on the at least one acquired value, the set of corrective actions including a product repair, a product downgrading, a product expertise and a product acceptance.

A method for producing a high-strength hot-dip galvannealed steel sheet, in which a high-strength steel sheet is used as a base material, includes a rolling step (x) of rolling a hot-dip galvannealed steel sheet with a coating layer having an Fe concentration of 8% to 17% by mass, and a heat treatment step (y) of heating the coated steel sheet which has been subjected to the rolling step (x) under the conditions satisfying the following formulae (1) and (2):

(273+T)×(20+2×log.sub.10(t))≥8000  (1)

40≤T≤160  (2) where T: heating temperature (° C.) of the coated steel sheet, and t: holding time (hr) at the heating temperature T.

An apparatus for cooling a steel sheet includes: an apparatus body provided spaced apart from a steel sheet in the conveying path of the steel sheet; and a cooling unit provided in the apparatus body to supply a cooling fluid. The apparatus body includes: a first edge body that faces a first edge portion extending a certain distance from one side end of the steel sheet toward the center of the steel sheet; and a second edge body that faces a second edge portion extending a certain distance from the other side end of the steel sheet toward the center of the steel sheet. The first and second edge bodies may have stepped cross-sections in a direction perpendicular to the conveying direction of the steel sheet.

Provided is a continuous hot-dip galvanizing apparatus comprising: a vertical annealing furnace having heating, soaking zone, and cooling zones therein; and a hot-dip galvanizing line downstream of the cooling zone. The heating, soaking, and cooling zones each have, in its upper portion, at least one upper hearth roll and, in its lower portion, at least one lower hearth roll. The soaking zone has a first and second humidified gas supply ports to supply a humidified gas having a dew point of 10° C. to 30° C. to the soaking zone. The first and second humidified gas supply ports are 1.0 m to 5.0 m lower than the center of the lower and upper hearth rolls, respectively, and overlap the steel sheet. The first humidified gas supply port is provided only for an ascending pass and the second humidified gas supply port is provided only for a descending pass.

Provided are a method of predicting hydrogen content in steel of a steel strip etc. Provided is, in a continuous galvanizing line that performs manufacturing processes including an annealing process, a coating process, and a reheating process of a steel strip, a method of predicting hydrogen content in steel of a steel strip downstream of the reheating process, including acquiring at least one parameter selected from operation parameters of the continuous galvanizing line and transformation rate information measured in at least one of the annealing process and the reheating process as input data, and predicting hydrogen content in steel of a steel strip downstream of the reheating process using a prediction model of hydrogen content in steel that has been trained by machine learning and that outputs information on hydrogen content in steel of a steel strip downstream of the reheating process as output data.

Equipment for the continuous hot dip-coating of a metal strip 9 including an annealing furnace, a tank 2 containing a liquid metal bath 3, a snout connecting the annealing furnace and tank 2, through which the metal strip 9 runs in a protective atmosphere and the lower part of the snout, the sabot 5, is at least partly immersed in the liquid metal bath 3 in order to define with the surface of the bath, and inside this snout, a liquid seal 6, an overflow 7 not connected to the snout, the overflow 7 including at least one tray 8, placed in the vicinity of the strip 9 when entering the liquid metal bath 3 and encompassed by liquid seal 6.