Abstract: A rolled steel product is given an elastic limit of 500 to 1200 MPa by selection of a particular steel composition and a particular heat treatment. The steel contains 0.10-0.50% C, 0.90-1.50% Mn, and 0.10-0.45% Si, and optionally 0.20-0.70% Ni, 0.10-0.80% Cr, and 0.02-0.10% V. The heat treatment consists of surface quenching from above the austenitization temperature by means of a fluid, the heat remaining in the product being sufficient to temper the martensite and/or bainite in the quenched surface.

Abstract: An assembly of light path deflectors is arranged so that radiation is transmitted along a folded optical path to an observation or measuring instrument (e.g. a pyrometer) from a point on a surface in an enclosure such as a blast furnace. The point is scanned along a scanning path (preferably spiral) which is uniformly distributed about the intersection of the surface with the sighting axis of the instrument, by simultaneously rotating the assembly and rotating at least one of the deflectors.

Abstract: Metal strip, particularly steel strip, is heated to above 250.degree. C. and quenched in a phosphating bath, at 80.degree. C. or more, containing one or more phosphates of the type Me (H.sub.2 PO.sub.4).sub.n, where Me=Zn, Ni, Mn, or an alkali metal, at a concentration of 1 to 20 g/l.

Abstract: To determine a dimension of an object, two emitted beams whose axes define a known angle are directed by means of a deflector onto points of the object related to the dimension to be determined so that when one beam falls on the first of two points defining the dimension the other beam falls on the second point. Light rays reflected by the two points are received as two beams by means of a receiver. The angle of incidence of the emitted beam is measured with respect to a direction. The angles made respectively by the axes of the two received beams with the axes of the emitted beams are measured. The dimension is calculated from the angles.

Abstract: To determine a dimension of an article, a beam is directed at the article by means of a first mobile deflector so as to scan the part of the profile of the article comprising the dimension to be measured. Rays reflected by the article are orientated in the direction of at least one receiver by means of a second mobile deflector. The deflectors are angularly moved at different speeds. The positions occupied by two points related with the dimension are determined. The dimension is calculated with respect to these points.

Abstract: The plant includes quenching apparatus having cooling means for directing cooling liquid onto a rolled product passing through the quenching apparatus from a rolling mill. The cooling liquid is removed from the rolled product, by a liquid, and optionally, by scraping or brushing. The quenched product is cut up, e.g. by shears, before passing to a still-air cooling area.

Abstract: A metal product, such as a steel strip or a mill roll, is cooled by spraying a coolant towards a surface of the product travelling along a given path, by means of cooling apparatus comprising two hollow caissons arranged one inside the other and rigidly connected together to constitute a unit. The unit is located adjacent the product surface and extends across the path of the product surface. Each caisson has a plurality of holes in a wall which is to face the product surface, each hole of the outer caisson being paired with a coaxially aligned hole of the inner caisson. A coolant sprayer is fixed in each pair of holes. Preferably, the sprayers are supplied with air from the inner caisson and water from the outer caisson, the water being atomized by the air.

Abstract: Molten iron is refined in a converter whose bottom has tuyeres with coaxial ducts. An oxidising gas such pure oxygen is blown through the inner duct while a protective fluid such as a hydrocarbon is blown through the outer duct. During tipping of the converter from a sampling position to an emptying position after the blow, entry of molten metal is prevented by blowing fluids through the ducts, at least one of the fluids being a gas substantially consisting of CO.sub.2. If a corrective blow is necessary after sampling, this may be carried out by blowing an oxidising gas through the inner ducts and CO.sub.2 (alone or with hydrocarbons) through the outer ducts.

Abstract: Metal strip, particularly steel strip, is heated above 300.degree. C. and immersed in a coating bath whose temperature is at least 80.degree. C. and which contains at least one metal salt, the strip being coated with a metal layer, e.g. Ni-based or Cr-based, by the coating bath.

Abstract: Before or during the coiling of cold-rolled sheet steel for stamping, the sheet steel is covered with a substance comprising an agent capable of reacting with amorphous carbon present on the sheet as a contaminant so as to form a volatile compound, such as carbon monoxide or carbon disulphide, during subsequent annealing of the coil. Suitable substances for forming carbon monoxide are (1) certain gels (e.g., gels deposited in the form of a very thin layer from a solution of a soluble silicate such as sodium, potassium, or lithium orthosilicate) which liberate water of adsorption on heating, as during annealing, which water of adsorption reacts with the carbon contaminant to form carbon monoxide; and (2) certain salts [e.g., Ba(OH).sub.2. 8H.sub.2 O, Ca(OH).sub.2, and Zr(OH).sub.4 ] which liberate water of crystallization or water of constitution on heating, as during annealing, which waters of crystallization and constitution react with the carbon contaminant to form carbon monoxide.

Abstract: A tubular steel section at a temperature, above Ac.sub.1, at which the steel contains at most 15% ferrite is subjected to martensitic and/or bainitic quenching followed by still air cooling. The effects of quenching are limited to a surface layer, internal and/or external, of the section. At the end of the quenching step the part of the section remote from the quenched surface layer or layers is at a temperature above 675.degree. C. which permits self-tempering of the quenched surface layer or layers at a temperature above 450.degree. C. and ensures transformation of residual austenite to a martensite-free structure.

Abstract: The elastic limit and breaking load of steel sections are improved by a process of surface quenching and self-tempering comprising a cooling stage followed by rapid cooling which is interrupted to allow the quenched surface layer of the section to be tempered by heat from non-quenched inner portions of the section. The rapid cooling is succeeded by a slow cooling.

Abstract: Cold-rolled steel sheet or strip (e.g. containing max. 0.15% C., max. 0.60% Mn, max. 0.020% Si, and 0.001-0.050% B) is heated to a temperature higher than its recrystallization temperature and then cooled by immersion in an aqueous bath at above 75.degree. C.The cooling by immersion consists of two successive stages, in the first of which cooling occurs at a rate of 25.degree.-180.degree. C./s to 200.degree.-425.degree. C., the product of the cooling rate v in .degree. C./s times the sheet or strip thickness e in mm being greater than 25, and in the second of which v is 90.degree.-500.degree. C./s and v times e is at least 35. Optionally a further annealing or overageing step comprises holding at 275.degree.-525.degree. C. for 30-250 s.

Abstract: A steel section 6 to 40 mm thick, emerging from a hot rolling mill at 1000.degree. to 800.degree. C. is surface quenched for 2 to 6 seconds at a cooling rate of the order of 1.5 to 5 MW/m.sup.2. During subsequent self-tempering of the quenched surface by heat from the remainder, the section tends to an equalization temperature of 500.degree. to 700.degree. C.

Abstract: The profile of a surface of an object is determined by scanning the line of intersection of this surface and a given plane transverse to the object. A radiation transmitter provides a transmitting beam, and a radiation receiver provides a receiving beam. Deflection means causes scanning movement of one or both of the beams so that a zone of intersection of the beams scans along a predetermined line and a detector in the receiver receives radiation transmitted from a source in the transmitter and reflected by the surface of the object. The deviation of the actual line of intersection from the predetermined line is determined from data supplied by the detector at a plurality of positions along the line of intersection.

Abstract: Wire rod is subjected to a cooling operation while emerging from a hot rolling mill. The rod is first cooled to a temperature of 850.degree. to 650.degree. C. and is then kept at substantially this temperature for a time sufficient for austenite to be transformed into ferrite. The rod is then cooled to a temperature of 625.degree. to 400.degree. C., and is kept at substantially this temperature, or allowed to cool slowly, for a time not shorter than 15 seconds and sufficiently long to permit precipitation of carbon in the form of carbides.

Abstract: A continuous casting process, in which the upper surface of the molten metal in the mold is covered by a protective powder, is controlled. The acceleration spectrum of the mold is recorded and compared with an ideal spectrum corresponding to optimum quality of the ingot skin. Any difference observed between the two spectra is taken up by modifying a parameter having an effect on the ingot quality at the time at which it is formed in the mold.

Abstract: At the outlet of the finishing stand of a rolling mill, a cooling apparatus is arranged to surface quench only the outer layer of the flat face of a steel section by a cooling fluid. The cooling conditions are adjusted so that, at the outlet of the cooling zone, the unquenched parts of the section are at a temperature still sufficiently high to temper the quenched face, and so that the austenite is transformed into ferrite and carbides in the unquenched parts of the section.

Abstract: Waste water from coke ovens is purified by passing the waste water and a stripping fluid through a stripping column in counterflow. Non-volatile ammonium compounds are removed in one region of the column, phenolic compounds are removed in another region, and volatile ammonium compounds are removed in yet another region. The region in which phenolic compounds are removed is disposed at such a location that no ammoniacal vapor can traverse it. An acid and a strong base are fed laterally into the column at two different levels.

Abstract: Liquid and gaseous phases are contacted in a column having a plurality of perforated plates spaced one above another. Each plate undergoes rotational or translational movement while at least one of its faces is subjected to a cleaning operation.