Abstract
Abstract Gradient metal materials with a nanostructured surface layer have a great potential for industrial applications due to their outstanding properties. The article studies the influence of a new combined deformation technology on the change in properties and gradient microstructure formation in copper bars. This combined technology consists of combining radial-shear broaching in a radial-shear rolling mill with traditional drawing. The laboratory experiment was carried out at room temperature on bars with a diameter of 30 mm. The copper bars obtained after 3 cycles of deformation were examined using transmission electron microscopy and EBSD analysis, tensile tests and microhardness measurements. Laboratory experiment showed that the use of radial shear broaching helps to reduce the number of deformation cycles and, as a result, reduce cyclicity of technological process, as well as increase the depth of structure development due to the penetration of compressive deformation along the cross section of the bar. During the drawing process, intense accumulation of deformation occurs in the surface zone, which improves strength and plastic properties of the bar. Accumulation of deformation is achieved through the simultaneous action of four sources of deformation: shear deformation, diameter reduction, torsion and broaching.