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.
Stress-strain curve construction for low-plastic alloys under severe plastic deformation conditions is considered. A material under investigation is cast bronze Cu85-Pb5-Sn5-Zn5. Experiments on upsetting and deep rolling were conducted. Based on these data, the initial hardening modular and the hardening modular at large strain were evaluated. Classic tests on determining an initial segment of stress-strain curve can lead to grate mistakes because shear band sliding can diminishes appreciably both yield stress and hardening modular. A correct methodology for stress-strain curve construction is proposed.
The complex approach to the microstructure and microhardness parameter of BrOCS 5-5-5 changing dependences out of hardening degree are presented. The acquired results correlate with the earlier research, but give us new knowledge about the microstructure and microhardness parameter value changes depending of the deformation degree. That allows predetermining the accumulated deformation degree at bush type hardening process, for example – plain bearing liners or structural elements in the form of axial symmetry tybes. The prediction of the microstructure and mechanical parameters – microhardness parameter value in dependence of accumulated degree in particular becomes possible. The microstructure research carried out allows predetermining the necessary deformation degree for the studied material for its further application.
The article considers a new method of sliding bearings inner surface hardening by plastic deformation in complex local loading of deformation zone conditions. The main aspects of experimental equipment construction and experimental research preparation are reviewed. The laboratory research results are presented.
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