Plastic deformation behaviors and mechanical properties of rolled rings of 20CrMnTi alloy in combined radial and axial ring rolling

• Three kinds of plastic deformation behaviors of rolled rings are found in the proposed process.
• With increasing λa, the circumferential strain of the rolled ring decreases and the axial strain increases.
• The rolled rings with the same final geometry may have different mechanical properties.

In this paper, a new combined radial and axial ring rolling process is proposed, in which a large increase in both the ring diameter and height can be achieved. Using the finite element (FE) method, the plastic deformation behaviors and mechanical properties of the rolled rings of 20CrMnTi alloy in combined radial and axial ring rolling are numerically investigated. It is found that under different axial rolling ratio λa and radial rolling ratio λr, there are three kinds of plastic deformation behaviors during the process. The first one is that when λa = 1 and λr > 1, the ring produces the deformation of thickness reduction and diameter expansion and its height basically remains unchanged. The second one is that when λa > 1 and λr > 1, the ring produces the deformation of thickness reduction, diameter expansion and height increase. The third one is that when λa > 1 and λr = 1, the ring produces the deformation of thickness reduction, outer diameter constancy and height increase. Owing to these plastic deformation behaviors, the axial and circumferential strain distribution of the rolled rings with the same final geometry is different. To evaluate the mechanical properties of these rolled rings, the compression and tensile tests have been carried out numerically and it is found that the rolled rings with the same final geometry may have different mechanical properties due to the different axial and circumferential strain distribution and the proposed combined radial and axial ring rolling process can thus be adopted to manufacture the rings with the same final geometry but different mechanical properties.