Development and Experimental Testing of a New Technology for Producing Screw Fittings from Bar Scrap of Ferrous Metals

Abstract

One of the simplest and most frequently used methods of recycling ferrous scrap is its remeltingand further reuse. But at the same time, in some countries of the world, another method of processing ferrousscrap has entered into practice, namely, recycling of some metal products that have served their service life byvarious methods of hot pressure treatment to obtain a finished commercial product. In our opinion, this methodof processing ferrous scrap and alloys can be attributed to "green" technologies, as it allows you to make a smallcontribution to improving the environmental situation in the world. This work, carried out within the frameworkof grant № AP14869135, funded by the Science Committee of the Ministry of Science and Higher Education ofthe Republic of Kazakhstan, is devoted to the development and research of a new technology for processingscrap in the form of pieces of reinforcement made of 25G2S steel to obtain high-quality finished metal productsin the form of screw fittings. The developed technology included two stages. At the first stage, thereinforcement pieces are performed on a radial-shear rolling mill to obtain conventional rods of the desireddiameter and create initial conditions for the formation of a gradient ultrafine-grained structure in the resultingscrew profile. The second stage is the direct production of screw fittings with a gradient ultra-fine-grainedstructure on a combined installation. Metallographic studies have shown that after the implementation of thesecond stage of obtaining screw fittings, a gradient structure is observed in 25G2S steel in the longitudinaldirection, with equiaxed grains (ranging in size from 11-14 μm) in the peripheral region and with elongated,directional-oriented grains in the central region of the resulting reinforcement.