Moving metal strips can be heat treated with any number or combination of dimensionally variable tempers across widths, lengths, or thicknesses of a metal strip. To provide dimensionally variable heat treatment, an apparatus can include one or more heating units suitable to increase the temperature of a metal strip moving proximate the apparatus to a heat treatment temperature. The apparatus can also include one or more cooling units positioned near the heating units to absorb heat and cool the metal strip to minimize the amount of heat transferred from a first region of the metal strip that is to be treated to a second region of the metal strip that is not to be treated.

A method comprises: annealing a steel sheet by conveying the steel sheet through a heating zone, a soaking zone, and a cooling zone in the stated order in an annealing furnace; and then applying a hot-dip galvanized coating onto the steel sheet discharged from the cooling zone. Reducing or non-oxidizing humidified gas and reducing or non-oxidizing dry gas are supplied into the soaking zone. A CO gas concentration is measured using a CO gas concentration meter provided in an exhaust portion for gas in the soaking zone. A decarburized layer thickness of the steel sheet is calculated from the measured CO gas concentration. At least one of a flow rate and a dew point of the humidified gas is controlled so that the calculated decarburized layer thickness is less than or equal to a predetermined thickness.

Disclosed herein are systems and methods for engineering a metal substrate surface via a dry chemical deposition technique. Also described herein are the resulting surface engineered metal substrates. More particularly, disclosed are surface engineered metal substrates having thin films deposited via flame pyrolysis of a mixture of a gas mixture comprising an oxidizer and a combustible gas, a chemical precursor comprising a silicon-containing compound and/or a phosphorus-containing compound, and a chemical additive.

A steel sheet having a steel microstructure including, by area %, martensite in a range of 20% or more and 100% or less, ferrite in a range of 0% or more and 80% or less, and the balance being 5% or less. A residual stress generated at the transverse center of the steel sheet when the steel sheet is subjected to a V-bending process is 800 MPa or less. A residual stress generated at the transverse end of the steel sheet when the steel sheet is subjected to a V-bending process is 90% or more and 110% or less of the residual stress generated at the transverse center of the steel sheet. The maximum amount of warpage of the steel sheet sheared to a length of 1 m in the longitudinal direction is 15 mm or less.

An apparatus for manufacturing a stress relieved length of steel having an oxidised surface layer includes: a heating chamber; a reaction chamber coupled to the heating chamber; and a conveying mechanism conveying the length of steel along a path through the heating chamber and reaction chamber. The heating chamber includes a heating apparatus arranged to heat the length of steel in a heating portion of the path. The apparatus further includes a control means including a sealed unit defined by the heating chamber and the reaction chamber and arranged to control both the temperature of the length of steel and the atmosphere to which the length of steel is exposed in an oxidisation portion of the path within the reaction chamber in which the oxidised surface layer is formed. A method of manufacturing a stress relieved length of steel having an oxidised surface layer is also disclosed.

An apparatus for manufacturing a stress relieved length of steel having an oxidised surface layer includes: a heating chamber; a reaction chamber coupled to the heating chamber; and a conveying mechanism conveying the length of steel along a path through the heating chamber and reaction chamber. The heating chamber includes a heating apparatus arranged to heat the length of steel in a heating portion of the path. The apparatus further includes a control means including a sealed unit defined by the heating chamber and the reaction chamber and arranged to control both the temperature of the length of steel and the atmosphere to which the length of steel is exposed in an oxidisation portion of the path within the reaction chamber in which the oxidised surface layer is formed. A method of manufacturing a stress relieved length of steel having an oxidised surface layer is also disclosed.

Provided is a cooling device, where a hot-finish-rolling mill includes a plurality of nozzles which spray cooling water toward one of or both of upper and lower surfaces of a hot-rolled steel sheet just after rolled by rolling stands, the nozzles are provided on the inside of the upper and lower guides or adjoining to the guides on a downstream side, and a nozzle spray distance changes depending on a position of the nozzle in a rolling direction, wherein a spray angle of the nozzle at a position whose nozzle spray distance is the largest is smaller than a spray angle of the nozzle at a position whose nozzle spray distance is the smallest, and the spray angle of the nozzle becomes the same or smaller as the nozzle spray distance becomes large.

A gas blower device for blowing gas onto a surface of a traveling strip includes a plenum in the form of a hollow box for containing gas and comprising two side surfaces, a back surface and a front surface opposite to the back surface. The front surface having a profile of convex type symmetry with respect to a mid-plane perpendicular to the plane of the strip, so that a middle ridge of the front surface is located at the smallest distance from the plane of the strip. The front surface further presenting multiple tubular nozzles protruding at the front surface and having a gas outlet orifice facing in use the traveling strip. All the outlet orifices are essentially in a plane parallel to the strip plane. The gas blower device further includes a gas intake tube for feeding the plenum with gas.

A gas blower device for blowing gas onto a surface of a traveling strip includes a plenum in the form of a hollow box for containing gas and comprising two side surfaces, a back surface and a front surface opposite to the back surface. The front surface having a profile of convex type symmetry with respect to a mid-plane perpendicular to the plane of the strip, so that a middle ridge of the front surface is located at the smallest distance from the plane of the strip. The front surface further presenting multiple tubular nozzles protruding at the front surface and having a gas outlet orifice facing in use the traveling strip. All the outlet orifices are essentially in a plane parallel to the strip plane. The gas blower device further includes a gas intake tube for feeding the plenum with gas.

Disclosed is a treatment line for the continuous treatment of metal strips having a dual purpose, i.e. for producing strips that are annealed and dip-coated with a metal alloy and for producing strips that are annealed and not coated, comprising a dual-purpose cooling tower, i.e. for cooling strips that are annealed and not coated in a non-oxidizing atmosphere and for air-cooling strips that are annealed and coated.