Development of Asymmetric Rolling as a Severe Plastic Deformation Method: A Review

This paper presents an overview of the latest trends in the development of severe plastic deformation (SPD) using rolling methods. From many scientific works, it is known that severe plastic deformation provides intense grain grinding up to ultrafine and nanosized grains during multi-cycle deformation. It is also possible to obtain a uniform or gradient grain distribution over the cross-section of the workpiece. During SPD processes, the strength parameters can be increased several times. Of all the methods considered, asymmetric rolling has become the most widespread owing to its simple implementation in production conditions. Most of the known methods and devices for asymmetric rolling are designed for deformation in rolls with a smooth barrel, while the use of rolls with a relief surface allows the processing of metal to obtain a higher level of equivalent strain. Ensuring a high asymmetry level when rolling in relief rolls allows, in addition to the development of shear strain in two transverse directions (height and width), it also provides an additional level of shear strain in the longitudinal direction. In addition to the speed asymmetry, the rolling scheme in relief rolls is also suitable for the implementation of geometric asymmetry when one of the relief rolls has a reduced or increased diameter while maintaining the relief geometry on the roll surface.