Centre De Recherches Metallurgiques-centrum Voor Research in De

Mario Economopoulos

Yves Jean Respen

Paul Andre Cosse

Jean Y Respen

Stephane H Wilmotte

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.

Plants for treating rolled steel products

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.

Apparatus for improving the quality of steel sections

Steel wire rod leaving the last stand of a rolling mill is quenched to between 850.degree. C and a temperature corresponding to the nose of the curve representing the start of the transformation of austenite to ferrite-pearlite plotted with respect to time and temperature. The wire rod is then subjected to a second cooling while in the form of loose turns passing along a given path. The variation of the temperature of the wire rod along this path is observed, and the position is detected at which a temperature increase occurs owing to recalescence. At this position the wire rod is subjected to supplementary cooling.

Processing wire rod

In the rolling mill the temperature of the product is reduced to between Ac.sub.3 and Ac.sub.3 + 150.degree. C before it enters the finishing stands. The product emerging from the finishing stands is quenched to provide a surface layer of martensite and/or bainite. Subsequently the heat of the core of the product is allowed to raise the temperature of the surface layer to between 450.degree. and 750.degree. C, so that the quenched layer is tempered.

Producing rolled steel products

Steel rod or bar at the exit of the finishing stand of a hot rolling mill is superficially quenched, so that the surface layer of the rod or bar is given a bainitic or martensitic structure. Immediately after quenching, the core of the rod or bar is at about 850.degree. C and, therefore, still austenitic. Subsequent air cooling allows the austenite to transform to ferrite and carbides, while the surface layer is tempered by the heat transferred to it from the core.

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Liege, Belgium

Mario Economopoulos