Numerical Simulation and Experimental Validation of Surface Roughness by the Smoothing Small Ball-Burnishing Process

The smoothing ball-burnishing process has commonly been used as a post-processing method to reduce the irregularities of machined surfaces. However, the mechanism of this process has rarely been examined. In this study, a simulation procedure is proposed to predict the surface roughness of a burnished workpiece under varying burnishing forces. The roughness of the workpiece surface was firstly approximated by parabolic functions. The burnishing process was then numerically simulated through two steps, namely the elastic–plastic indentation of the burnishing ball on the workpiece’s surface, and the sliding movement of the burnishing tool. The results of the simulation were verified by conducting small ball-burnishing experiments on oxygen-free copper (OFC) and Polmax materials using a load cell-embedded small ball-burnishing tool. For the OFC material, the optimal burnishing force was 3 N. The obtained experimental surface roughness was 0.18 μm, and the simulated roughness value was 0.14 μm. For the Polmax material, when the burnishing force was set at its optimal value—12 N, the best experimental and simulated surface roughness were 0.12 μm and 0.10 μm, respectively.

DIAGNOSTICS OF THE PHYSICAL AND MECHANICAL PROPERTIES OF THE METAL BY THE PARAMETERS OF THE ELASTIC-PLASTIC INDENTATION OF A SPHERICAL INDENTER

The paper describes non-destructive methods for determining the physical and mechanical properties of metals based on the regularities of elastic-plastic indentation of a spherical indenter into the test material. Using the proposed methods makes it possible to construct a diagram of true tensile stresses based on the results of a single indentation of a spherical indenter.

OPERATIONAL CONTROL OF THE LIMIT UNIFORM PLASTIC DEFORMATION

The paper presents a non-destructive method for determining the limit uniform narrowing of structural steels by the parameters of the elastic-plastic indentation of a spherical indenter. An acceptable accuracy of the method for engineering assessment of the plastic properties of the material of parts is shown.

Processing of Graphic Information in the Study of the Microhardness ofthe Sintered Sample of Chromium-containing Waste

The results of graphic information processing and investigation of the microhardness of the sintered sample from chromiumcontaining waste are presented. Currently, one of the main directions of development of engineering technology is the improvement of existing and the development of new waste-free, environmentally friendly, material-saving production processes. Powder metallurgy is a branch of technology, including the manufacture ofpowders from metals and their alloys and the preparation of blanks and products from them without melting the main component. In most cases, new materials are created in order to provide the optimal combination ofproduct price and operational characteristics. Microhardness is the resistance to plastic indentation (usually on a flat surface) of a solid tip in the shape of a cone or a pyramid made of diamond. With the help of microhardness, they control very small parts, test and sort out watch, instrument and other products. The aim of the work was to study the microhardness of a sintered sample.

Elasto-Plastic Indentation of Auxetic and Metal Foams

The elasto-plastic indentation of auxetic and metal foams is investigated using the finite element method. The contributions of yield strain, elastic, and plastic Poisson’s ratio on the indentation hardness are identified. For a given yield strain, when the plastic Poisson’s ratio is reduced from 0.5, the indentation hardness decreases first and then increases. This trend was found to be valid for a wide of yield strains. For yield strains less than 0.08, the hardness of auxetic materials is much larger when compared with materials having positive plastic Poisson’s ratio. As the plastic Poisson’s ratio approaches −1, the elastic deformations dominate over the plastic deformations. The plastic dissipation, when compared with the elastic work, is lower for materials with negative Poisson’s ratio. There is no effect of elastic Poisson’s ratio on the indentation hardness when the plastic Poisson’s ratio is more than −0.8. When the plastic Poisson’s ratio is less than −0.8, the hardness increases with a decrease of elastic Poisson’s ratio. The plastic dissipation per unit strain energy is maximum for materials with vanishing plastic Poisson’s ratio.