GB749841A - Improvements in and relating to the production of cold worked reinforcement steel bars - Google Patents

Abstract

749,841. Altering physical structure of rods and bars. KAZINCZY, G. DE. May 19, 1953 [May 20, 1952], No. 14089/53. Drawings to Specification. Classes 83 (2) and 83 (4). A method for producing a cold-worked reinforcement steel bar for concrete structures comprises subjecting a single, hot-rolled bar in cold condition to one, or simultaneously or successively a plurality of working operations to permanently deform the bar and finally to a stretching operation with a force which causes greater stress than the stress at yield point of the hot-rolled material such that the permanent elongation due to this stretching is less than the elongation at yielding but that in steel qualities in which the said elongation is less than one per cent the permanent elongation shall not exceed one per cent. The main function of the first cold working operation is to raise the ultimate tensile strength of the bar and such first cold working may comprise twisting in one direction; twisting successively in opposite directions; bending repeatedly one or several times successively in opposite directions by passing the bar between one or a plurality of a series of rollers; stretching followed by twisting; bending followed by twisting; stretching followed by bending; cold rolling; cold rolling followed by twisting or bending to and fro the cold-rolling providing, if desired, ribs, cams or flanges on the bar. The last working operation, namely the stretching, is performed either immediately after the first cold working or later after cold or warm ageing of the steel resulting from the first cold working by which ageing both the elastic limit and the yield point are increased. The final stretching may be postponed until the bars can be tensioned during their mounting in the structural work.