Deep Hardening of Inner Cylindrical Surface by Periodic Deep Rolling - Burnishing Process

Severe surface plastic deformation is one of the methods to improve the mechanical behavior of metallic components, because such a treatment generates a hardened near-surface layer with compressive residual stresses. As is well known, deep rolling (DR) stands out against a background of the others mechanical techniques owing to maximum values of hardness, residual stress and hardening depth attained. In this work, an accomplished version of DR is proposed, which may be regarded as a superposition of DR and burnishing (B) processes in order to elevate those characteristics up to larger values. In contrast to consecutive application of DR and B techniques, the new approach allows to alter them multiply within one and only technological process with no increasing the working duration and without the need of any additional equipment. The working principles of the device are described. The dependences “depth-hardness†are presented. Numerical assessment of the residual stress is performed. The micro-photographies demonstrate an increase in the structural homogeneity of the near-surface layer material. The results indicate that the newly developed technique attains its main goals.