A method for determining the ferrite phase fraction x.sub.a after heating or when cooling a steel strip (2) in a metallurgic system. Also, a device for carrying out the method. A method by which the ferrite phase fraction in the steel strip (2) can be determined online, quickly and easily, includes measuring a width w.sub.1 and a temperature T.sub.1 of the steel strip (2), wherein the steel strip (2) comprises a ferrite phase fraction x.sub.a 1 during the measurements; heating or cooling the steel strip (2); when heating the steel strip (2) a phase conversion at least in part occurs, a.fwdarw.y from the ferrite state a into the austenitic state y and when cooling the steel strip a phase conversion at least in part occurs, from the austenitic state y into the ferrite state a; measuring of a width w and a temperature T of steel strip (2) converted at least in part; determining the ferrite phase fraction of the formula (I), wherein T.sub.0 is a reference temperature and a.sub.a and a.sub.y are the linear heat expansion coefficients of ferrite and austenite.

System and method for using fast response heaters to pre-heat metal before entering a metal treatment furnace, which may improve control over metal processing, especially in response to changes in material, mass flow rate, line speed, and/or desired treatment process. Fast response heaters may be used with control systems to adjust the output of the fast response heater based on operator inputs, direct or indirect sensing of process parameters, and/or the use of thermal models to quickly adjust fast response heater output while a metal treatment furnace remains at a constant temperature or slowly transitions into a new operating state. The resulting gains in process control result in higher quality products, reduced scrap, and increases in line speed and output.

A high-strength air-hardenable multiphase steel having minimal tensile strengths in a non air hardened state of 750 MPa and excellent processing properties, said steel comprising the following elements in % by weight: C0.075 to 0.115; Si0.200 to 0.300; Mn1.700 to 2.300; Cr0.280 to 0.4800; Al0.020 to 0.060; N0.0020 to 0.0120; S0.0050; Nb0.005 to 0.050; Ti0.005 to 0.050; B0.0005 to 0.0060; Ca0.0005 to 0.0060; Cu0.050; Ni0.050; remainder iron, including usual steel accompanying smelting related impurities, wherein for a widest possible process window during continuous annealing of hot rolled or cold rolled strips made from the steel a sum content of M+Si+Cr in the steel is a function of a thickness of the steel strips according to the following relationship: for strip thicknesses of up to 1.00 mm the sum content of M+Si+Cr is 2.350 and 2.500%, for strip thicknesses of over 1.00 to 2.00 mm the sum of Mn+Si+Cr is 2.500 and 2.950%, and for strip thicknesses of over 2.00 mm the sum of Mn+Si+Cr is 2.950 and 3.250%.

A method for operating an annealing furnace to anneal a metal strip provides that, initially, at least one target material property (MP.sub.Target) is specified for a point or a section of the metal strip after passing through the annealing furnace. In addition, information (E) on the metal strip is provided before or in the annealing furnace. A calculation of a target temperature distribution (T.sub.Target) and/or a target speed (V.sub.Target) of the metal strip in the annealing furnace is then carried out with the assistance of a computer-aided model as a function of the target material properties and the specified information. The target temperature distribution and/or target speed calculated in this manner is/are subsequently set in the annealing furnace in order to transfer the material property of the metal strip behind the annealing furnace to the desired target material property MP.sub.Target.

An ultra-high-strength air-hardenable multiphase steel having minimal tensile strengths in a non air hardened state of 950 MPa and excellent processing properties, includes the following elements in % by weight: C0.075 to 0.115; Si0.400 to 0.500; Mn1,900 to 2,350; Cr0.200 to 0.500; Al0.005 to 0.060; N0.0020 to 0.0120; S0.0030; Nb0.005 to 0.060; Ti0.005 to 0.060; B0.0005 to 0.0030; Mo0.200 to 0.300; Ca0.0005 to 0.0060; Cu0.050; Ni0.050; remainder iron, including usual steel accompanying smelting related impurities, wherein for a widest possible process window during continuous annealing of hot rolled or cold rolled strips made from said steel a sum content of M+Si+Cr in said steel is a function of a thickness of the steel strips according to the following relationship: for strip thicknesses of up to 1.00 mm the sum content of M+Si+Cr is 2.800 and 3.000%, for strip thicknesses of over 1.00 to 2.00 mm the sum of Mn+Si+Cr is 2.850 and 3.100%, and for strip thicknesses of over 2.00 mm the sum of Mn+Si+Cr is 2.900 and 3.200%.

A continuous annealing apparatus includes: a pre-treatment device to prepare a strip unwound from a coil; a heating device to heat the strip prepared by the pre-treatment device; a heat holding device to isothermally maintain the strip heated by the heating device; a first cooling device to cool the strip heat-maintained by the heat holding device; an annealing device including a first annealing device for annealing the strip, which, is cooled by the first cooling device, for a first time, and a second annealing device for winding the strip, which is cooled by the first cooling device, into a coil and then unwinding the coil into the strip again after annealing for a second time; a second cooling device to cool the strip annealed by the first annealing device or the second annealing device; and a post-treatment device to wind the strip cooled by the second cooling device into the coil.

A method for manufacturing a thermally treated steel sheet is described. The method includes: A. a preparation step including: 1) a selection substep, wherein the chemical composition and m.sub.target are compared to a list of predefined products, which microstructure includes predefined phases and predefined proportion of phases, and selecting a product having a microstructure m.sub.standard closest to m.sub.target and a predefined thermal path TP.sub.standard to obtain m.sub.standard, 2) a calculation substep, wherein at least two thermal path TP.sub.x, each TP.sub.x corresponding to a microstructure mx obtained at the end of TP.sub.x, are calculated based on the selected product of step A.1) and TP.sub.standard and the initial microstructure mi of the steel sheet to reach m.sub.target, 3) an selection substep, wherein one thermal path TP.sub.target to reach m.sub.target is selected, TP.sub.target chosen from TP.sub.x and selected such that m.sub.x is the closest to m.sub.target, B. a thermal treatment step, wherein TP.sub.target is performed on the steel sheet.

Method for thermally treating a scrolling steel strip (5), said method comprising the following steps: heating the strip (5) in a zone for heating with a direct flame (10); temperature homogenisation of the strip (5) in a homogenisation chamber (20) comprising at least one radiant heating tube (25), so as to homogenise the strip (5) in temperature after the passing thereof into the zone for heating with a direct flame (10) of the preceding step; oxidation of the strip (5) in an oxidation chamber (30) with an oxidising atmosphere having an oxygen volume concentration greater than 1%; reduction of the strip (5) in a reduction zone (40).

A continuous annealer for wire is disclosed, and specifically for annealing and recrystallizing a wire in a continuous process. The continuous annealer for wire comprises: two contact discs for contacting a first wire portion extending therebetween; an annealing zone situated between the two contact discs; and annealing means for annealing the first wire portion in the annealing zone, as a result of which a first partial recrystallisation process in the first wire portion takes place in the annealing zone. A recrystallisation zone is situated downstream of the second contact disc, wherein, downstream of the annealing zone, the first wire portion passes through the recrystallisation zone as the second wire portion, and a second partial recrystallisation process takes place in the second wire portion. The wire has the opportunity to recrystallize further after leaving the annealing zone without further heating. By extending the recrystallisation time, the recrystallisation temperature can be reduced accordingly. As a result, the same degree of recrystallisation can be achieved overall with a significantly lower input of energy than when the wire is cooled immediately after leaving the annealing zone.

A device and a method for producing a continuous strip-shaped composite material. For this purpose, a base material, which is produced using at least one casting machine as a continuous strand, in particular made of steel, and providing at least one cladding material, which is unwound in the form of at least one metal strip by a coil unwinding unit are provided. Subsequently, a slab which has formed by solidification from the strand produced by the casting machine and the metal strip unwound by the coil unwinding unit, in the hot state are brought together, wherein the materials, which are moved in the direction toward one another, formed from the slab and the unwound metal strip are hot rolled, so that a single continuous strip-shaped composite material is thus produced by roll cladding. The base material is continuously cast in the vertical direction in the casting direction.