Study of the processing of long-length billets by continuous free bending

Abstract

This paper investigates the features of deformation processing by continuous free bending in rollers, aimed at enhancing the mechanical properties of long-length metallic billets without any change in their cross section. As the material for the investigation, we selected a chromium-zirconium bronze for electrical engineering applications, used, for example, for the production of contact wires that require high mechanical characteristics. Computer simulation reveals that during the processing by continuous free bending, a gradient field of accumulated strain is formed, with maximum values in the peripheral region and with minimum values in the center of the billet. It is found that during bending, by the 6th cycle the peripheral layers of the billet accumulate a strain of e~2, and the damage reaches a value of ~1. In the process of verification by means of a physical experiment, cracks emerge on the billet surface during the 6th cycle, confirming the simulation data. Structural analysis shows that during multi-cycle processing by this method, a gradient type of structure is formed. An important advantage of the processing by continuous free bending is the enhancement of the mechanical properties of long-length samples without any reduction in the cross-sectional area: e.g., after 4 processing cycles the ultimate tensile strength increased from 250±20 to 380±20 MPa, and the variation of the cross-sectional area was ~5-7%. The obtained results are in agreement with some principles of severe plastic deformation processing.