Determination of porosity functions in the pressure treatment of iron-based powder materials in agricultural engineering

Abstract

One of the most effective ways to obtain products with the required performance characteristics is the cold plastic deformation of porous workpieces. The relevance of the subject under study is due to the need to increase the reliability of the stress-strain state assessment during the plastic processing of porous workpieces by clarifying the porosity functions. The purpose of the study is to develop a method for describing the mechanical characteristics of porous bodies by single functions, the nature of which is determined by the properties of the base material and does not depend on the initial porosity. Analytical, numerical, experimental, and computational methods using modern specialised software systems were used to examine the processes of plastic deformation. The study presents a method for describing the mechanical characteristics of porous bodies with single functions. A set of interrelated methods and techniques is based on the basic provisions of the mechanics of plastic deformation of porous bodies and allows obtaining reliable porosity functions for this material, by clarifying theoretical dependencies by experimental studies. Therewith, experimental data were obtained in experiments on axisymmetric upsetting of cylindrical samples without friction at the ends. Based on the conducted theoretical studies, porosity functions for iron-based materials are obtained. Samples of five different initial porosities were used for the study. As a result of processing experimental data, final expressions for the porosity functions of the iron-based powder workpiece material are obtained. The study also presents a method for calculating the accumulated deformation of the base material. Flow curves for iron-based powder materials are plotted. The obtained results will allow formulating the practical recommendations for the development of technological processes for the plastic processing of powder materials by pressure to obtain products with specified physical and mechanical properties

Keywords

• material
• porosity function
• pressure treatment
• cold plastic deformation
• flow curve
• stress