Continuous annealing equipment (1) including a cleaning device (11, 12) for performing a cleaning treatment on a steel strip (S) and an annealing device (12) for performing an annealing treatment on the steel strip (S) comprises an exhaust gas passage (31, 41) through which an exhaust gas discharged from the annealing device (12) flows, a solution circulation passage (32, 51) through which a cleaning solution used in the cleaning device (11, 12) circulates, and a heat exchanger (53) which forms a part of the solution circulation passage (32, 51) and contacts with the exhaust gas.

A method for continuously cleaning a moving strip in a cleaning installation including a tank containing an aqueous solution, at least a roll immerged in the aqueous solution for guiding the strip into the tank, at least an ultrasound emitter a feed for feeding an aqueous solution inside the tank, a tank emptier for emptying the tank, an aqueous solution estimator for estimating the aqueous solution level in the tank, a distance calculator for calculating, for each ultrasound emitter, its distance to the aqueous solution level and a power controller for controlling the power of the at least one ultrasound emitter including the following steps, performed continuously: estimating the aqueous solution level in the tank, calculating for each ultrasound emitter its distance to the aqueous solution level, comparing for each ultrasound emitter its distance to the aqueous solution level to a determined threshold.

A cleaning plant for hot-rolled metal strips provided with a surface oxide layer, the plant comprising unwinding means for unwinding at least one coil of rolled strip and pickling means for pickling said rolled strip; wherein there are provided measuring means for measuring the thickness of the surface oxide layer, arranged between said unwinding means and said pickling means; and wherein gaseous hydrogen detection means are provided to detect the presence of gaseous hydrogen in fumes produced by said pickling means. A corresponding cleaning method is also claimed.

An acid solution preparation device is an acid solution preparation device for preparing an acid solution used for pickling of a steel plate, the device including a sealed tank for storing the acid solution, a gas supply part for supplying an oxygen-containing gas from outside of the sealed tank to the sealed tank, and a purge part for discharging a gas in the sealed tank to the outside.

A pickling apparatus for pickling a strip of metal being conveyed is equipped with: a pickling tank for storing an acid solution; a surrounding part disposed in the pickling tank so as to surround the strip immersed in the acid solution in the pickling tank; and an oxidant supply part for supplying a liquid oxidant toward an inside of the surrounding part.

A process control system according to one embodiment of the present invention comprises: a first system for generating thickness information about an internal defect layer included in a carbon steel product; and a second system which receives the thickness information about the internal defect layer from the first system through a network, and which controls an etching process for removing at least a part of the internal defect layer from the carbon steel product by using the thickness information about the internal defect layer, wherein the first system provides the second system with a calculation module necessary for the second system to control the etching process, and the second system provides the first system with the information necessary for the first system to update the calculation module.

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%.

A cleaning plant for hot-rolled metal strips provided with a surface oxide layer, the plant comprising unwinding means for unwinding at least one coil of rolled strip and pickling means for pickling said rolled strip; wherein there are provided measuring means for measuring the thickness of the surface oxide layer, arranged between said unwinding means and said pickling means; and wherein gaseous hydrogen detection means are provided to detect the presence of gaseous hydrogen in fumes produced by said pickling means. A corresponding cleaning method is also claimed.