Control of ultrafine microstructure by single-pass heavy deformation and cold forging of metal

A hot extrusion system with controlled cooling is investigated in this study. This system is used with the aim of manufacturing steel and other metal products with ultrafine microstructures by single-pass heavy deformation followed by controlled cooling. The continuous formation of bulk materials with the desired geometry and microstructure could be realized using the proposed system or by adding hot rolling stands after processing using the proposed system. Microstructure evolution during and after heavy single-pass deformation is examined through a series of experiments involving the hot extrusion of plain carbon steel followed by controlled cooling. The effects of severe plastic deformation on grain refinement and the mechanical properties of the formed products are discussed. It is clear that the use of the proposed system is helpful for the grain refinement of a cast microstructure. Also, ultrafine-grain steel with a grain diameter of 3 μm can be formed using the proposed system. Finally, the formability of the ultrafine-grain steel manufactured using the proposed system is examined by a cold-forging experiment.