The invention is directed towards methods and apparatus for improving the accuracy of monitors measuring the property of spray water used to cool a molten metal strand in a continuous casting operation. The method utilizes a highly effective slid-sieve to remove particles from sample water that would otherwise jam the monitor or would break the monitor. This particle removal results in the monitor providing more accurate measurements which in turn results in lower operating expenses, reduced maintenance costs, and production costs.

Monitoring of a line system (1) in which a liquid medium (3) is guided in a line (2). The current pressure of the liquid medium (3) in the line (2) and in the associated current flow are sensed at sensing times. The two values are fed to a computing unit (5). The computing unit (5) calculates a theoretical flow of the liquid medium (3) in the line (2) from the sensed current pressure by taking into account a specified flow function. The flow function describes a physical relationship between the theoretical flow of the liquid medium (3) and the current pressure of the liquid medium (3). The computing unit (5) determines an individual degree of clogging on the basis of the current flow and the theoretical flow. On the basis of a number of determined individual degrees of clogging and by using stochastic methods, the computing unit (5) calculates an interval within which a degree of clogging of the line system (1) lies with a probability to be defined. The line system (1) is monitored by using the size of the interval and/or the position of the interval with respect to first limits for the degree of clogging that are defined beforehand.

A preparation method for preparing cooling water which aims to reproduce a target cooling water by using at least two aqueous solutions selected from an industrial water solution, a cationic ion exchange resin-treated water solution, a demineralized water solution and an aqueous solution containing Mg.sup.2+ and Ca.sup.2+ ions; a casting method using the cooling water obtained according to the preparation method; and a casting device (100) including the preparation device.

This steel sheet has a predetermined chemical composition, a microstructure contains, in terms of a volume fraction, ferrite: 10% to 75%, martensite: 20% to 90%, retained austenite: 0% to 5%, bainite and bainitic ferrite in total: 0% to 50%, and pearlite: 0% to 5%, a proportion of unrecrystallized ferrite in the ferrite is 0% to 25%, cementite that is contained in the martensite satisfies a predetermined relational expression, a density of transition carbide included in the martensite is 1.010.sup.13 pieces/m.sup.3 or more, a density of coarse inclusion having an equivalent circle diameter of 10 m or more is 0.50 pieces/mm.sup.2 or less, in a surface parallel to the surface at a position of the sheet thickness deep from the surface in the sheet thickness direction, a ratio of a maximum value Hv.sub.max of Vickers hardness to a minimum value Hv.sub.min of the Vickers hardness is 1.40 or less, and an average value of minimum distances between peaks of the Vickers hardness in a distribution map of the Vickers hardness is 1.00 mm or less.

A plant to produce metal products, and a corresponding management method, where the plant includes a production line which includes a plurality of operating units, each provided with respective hydraulic circuits, selected from a melting unit, a casting unit, a rolling unit and a cooling treatment apparatus, and a water supply unit having a tank for the water connected to each of the hydraulic circuits and a plurality of water feed devices configured to feed water from the tank to respective hydraulic circuits.

A process that produces a microalloyed steel in an integrated casting-rolling plant having a continuous casting machine with a mold, a single- or multi-stand prerolling train, a finish-rolling train having a first stand group with at least one first finish-rolling stand and a second stand group having at least one stand cooler. A metallic melt is cast in the mold to obtain a partly solidified thin-slab strand, which is supported, deflected and cooled. The solidified thin-slab strand is rolled by the prerolling train to obtain a prerolled strip that is finish-rolled in the first stand group to obtain the finish-rolled strip, which is fed to the second stand group and force-cooled in the second stand group, the finish-rolled strip having a thickness that results in a cooling rate of the core of the finish-rolled strip in the second stand group greater than 20 C./s and less than 200 C./s.