Technological inheritance in metal forming

Abstract

Ogorodnikov V., Arkhipova T. Technological inheritance in metal forming. Material working by pressure. 2020. № 1 (50). Р. 28-32.
 Technological heredity in metal forming processes is accompanied by hardening, the appearance of residual stresses, a deformation gradient, residual plasticity and a number of other factors that determine the operational properties of the product. The influence of most factors of technological heredity on the mechanical properties of the material of products has been studied, however, the plasticity of a pre-deformed workpiece remains insufficiently studied. For a quantitative assessment, a calculation method is proposed, with the help of which it seems possible to determine the plasticity resource of pre-deformed blanks. The developed calculation apparatus is based on a fracture model based on a tensor description of damage accumulation. It allows for the known mechanical characteristics to predict the plasticity characteristics of pre-deformed blanks at any type of stress state. The proposed method assumes the use of plasticity diagrams, which describe the change in ultimate deformation depending on the stress state indicators. Plasticity diagrams are constructed for materials tested under conditions of linear or plane stress states (tension, compression, torsion). The practical significance of the results is evidenced by the assessment of the plasticity of steeply curved elbows obtained by the method of cold plastic deformation according to a combined scheme, including deforming pulling of a pre-willed workpiece. In this case, the workpiece in the form of a pipe was subjected to plastic bending. The proposed method makes it possible to assess the residual plasticity of the finished bend. A satisfactory convergence of the calculated and experimental data has been revealed.