Abstract: In the production of medium carbon steel wire rod, upon leaving the hot rolling mill, the rod is cooled in two phases. The first phase is operative as the rod moves at end-of-rolling speed along a cooling line disposed between the finishing block and feed rollers disposed at the entry of a head for placing the rod in overlapping turns on a conveyor, the cooling line being continuous--i.e. being devoid of air cooling breaks between consecutive intensive cooling sections, the length and capacity of the cooling line being such that the surface temperature of the rod at the end of the first phase is between, on the one hand, the start-of-martensitic-transformation temperature for the particular steel concerned and, on the other hand, the latter temperature plus 200.degree. C.

Abstract: At the exit from the hot rolling mill the rail temperature is reduced to a value not less than that at which the pearlite transformation begins in the rail head. From this temperature the continuously advancing rail is subjected to rapid cooling in a rapid cooling line. Subsequently the rail is cooled to ambient temperature. For a given rail head temperature at the extreme to the rapid cooling line, the length of the line, the speed of advance of the rail, and the average thermal flux density applied to the head, flange, and web of the rail are controlled so that the final mechanical properties of the rail head are obtained, although less then 60% of the cross-section of the head has undergone the austenite-pearlite transformation upon leaving the rapid cooling line, and differences in elongation between the head and the web and between the head and the flange are minimized.

Abstract: A method of measuring the water content of charge materials in a shaft furnace, such as a blast furnace, wherein a known quantity of material is introduced into the shaft furnace, the gases emerging from the throat of the shaft furnace are analyzed; and the results of this analysis are used to calculate the value of the water content of the charged material.

Abstract: The surface and/or subsurface defects of the surface to be treated are detected, preferably over the entire said surface. The defects are eliminated by scarfing with a torch and/or by milling, following which the treated surface is inspected and cleaned. The detection, elimination, inspection, and cleaning devices are maneuvered by means of programmable robots or automatons controlled by a computer. The process may be applied on-line to hot, moving products (e.g., rolled or continuous cast products).

Abstract: The plasma torch has a hot cathode (3) connectable to the negative poles of a main current course and of an arcing current source, an anode (2) connectable to the positive pole of the main current source, and an intermediate arcing electrode (6) connectable to the positive poles of both sources. An inert gas is introduced (at 8) between the cathode (3) and the arcing electrode (6). A plasma-producing gas is introduced (at 4) between the arcing electrode (6) and the anode (2). A fuel supply line (17) may open into the space between the arcing electrode (6) and the anode.

Abstract: Optical beams from lasers are directed towards the middle and edges of a hot rolled steel sheet by fixed mirrors and rotatable mirrors which allow for different sheet widths. The points of incidence of the beams are observed by photodiode cameras whose receiving axes are orientated by fixed mirrors and rotatable mirrors so that the points remain in the respective fields of observation of the cameras. The levels of the points are obtained by triangulation and are used in the calculation of the planarity of the sheet.

Abstract: A laser beam is focused as a cone whose apex is to be located on the surface of a part to be treated. A reference distance between the surface and a given point of the focusing element is determined, at which the apex is located on the surface. The actual distance between the surface and the given point is measured and the difference between the actual distance and the reference distance is determined. The focusing element is displaced so that the difference determined is cancelled.

Abstract: Hot reducing gases, mainly containing CO, H.sub.2, and optionally N.sub.2, as well as smaller quantities of H.sub.2 O and CO.sub.2, are injected through some of the tuyeres. Hot air, hot superoxygenated air, recycled gas, or combustion vapor containing sufficient CO.sub.2 is injected through the other tuyeres.

Abstract: The gas-sampling apparatus comprises at least two sampling probes at each sampling location and at least one sub-assembly for filtering the gas samples at each sampling location. A unit for processing and analyzing the gas samples is connected to all the sampling probes and is located as close as practicable to all the sampling locations.

Abstract: At the outlet of a hot rolling mill the temperature of a hot rolled rail is reduced to a value not lower than that at which the pearlitic transformation begins in the rail head. The continuously moving rail is then rapidly cooled to below 650.degree. C. so that at least 80% of the austenite-pearlite transformation has occurred at the end of rapid cooling. The rail is then cooled to ambient temperature.

Abstract: An apertured rotary member intermittently intercepts a laser beam directed at a given zone of a target. The apertures have inclined lateral walls which, during interception of the beam, deflect at least part of it to a further zone of the target.

Abstract: A continuously-taken sample of a dust-laden gaseous fluid is continuously passed through a filter for a given sampling period, this step being repeated at intervals. During each interval, while no fluid is passing through the filter, the filter is weighed after a hot dust-free gas has been passed through in order to dry the deposited dust. From the successive weights obtained, the weight of dust deposited during each sampling period is calculated.

Abstract: A sensor unit comprising two pyrometers arranged in respective chambers disposed side-by-side and open at one end, one chamber being substantially totally reflecting and the other substantially totally absorbing. Periodically, the unit is advanced to the immediate proximity of the product, the signals from the pyrometers are received after the response time of the pyrometers has elapsed, and then the unit is withdrawn to its initial position. The signals from the pyrometers are processed so as to provide a signal representing the emissivity of the product.

Abstract: Steel sheet is subjected to a thermal treatment as a result of which an oxide layer is formed. The sheet is pickled by contact with an organic acid solution (formic acid), containing at least 50 mg/l of iron, at a pH of 1.5 to 4 and at a temperature above a minimum value T.sub.m given by T.sub.m =20+(pH-1.5)32.

Abstract: A tuyere for injecting hot reducing gases into a furnace is provided with an inlet pipe and a plasma oven whose gas outlet axis is inclined to the longitudinal axis of the tuyere. The angles which the outlet axis of the plasma oven and the inlet pipe form with the said longitudinal axis are such that the longitudinal axis is parallel to the vector sum of the amount of movement of the gases from the plasma oven and the inlet pipe respectively .

Abstract: A wet welding electrode, for manual arc welding underwater, has a coating containing at least one oxidizing agent such as iron oxide, for neutralizing the embrittling effect of nascent hydrogen, and its core contains at least one constituent, e.g. aluminum oxide, aluminum and nitrogen, or copper, which results in the presence of hardening components in the weld deposit.

Abstract: The invention relates to a method of protecting devices designed for the galvanization of metal products, in particular for the galvanization of continuous drive cylinders used when galvanizing sheet on a single surface. A surface layer of the cylinders is coated with one or more oxide, one or more silicate, one or more zirconate, one or more mixed inorganic compound. Examples of the oxides include Mg, Ca, etc. Examples of the silicates include Al etc. Examples of the zirconates include Mg etc. Examples of the mixed inorganic compounds include serpentines, amphiboles, silicon carbide. The oxides are applied directly to the cylinder surface to be formed "in situ", for example, by heating in air to approximately 1000.degree. C.

Abstract: Metal strip is passed around a cylinder immersed in a bath of molten metal. Selection of one-sided or two-sided coating is made by selecting the position at which the strip enters and leaves the bath relative to the position at which the strip comes into and out of contact with the cylinder, by selecting the level of the bath surface or by moving an auxiliary roll.

Abstract: Metal sheet (cold-rolled steel sheet) contaminated with rolling oil is heated at a temperature higher than its recrystallization temperature in a naked flame furnace, e.g. of the incomplete combustion type. The heated sheet is then rapidly cooled by contact with an aqueous medium. The resulting sheet has considerably improved suitability for phosphate coating and painting, compared with sheet which is annealed after alkaline degreasing. The sheet is preferably treated with formic acid.

Abstract: During each period in which electrical power is supplied to the electrodes one determines whether the weld is subject to flash, by means of an accelerometer on one of the electrode supports. The frequency of occurrence of flash indicates the quality of the welding operation.