Bauman Moscow State Technical University, Moscow, Russia:

V. A. Demin, Professor at the МТ6 Department

Tula State University, Tula, Russia:
A. V. Chernyaev, Professor at the Department of Mechanics of Plastic Forming (MPF), e-mail: sovet01tsu@rambler.ru
V. I. Platonov, Associate Professor at the Department of MPF
V. A. Korotkov, Senior Researcher at the Department of MPF

The authors of this paper developed a new technique for processing experimental data from experiments that looked at building hardening curves and determining the coefficients of anisotropy developing in sheet material at high temperatures. The existing technique is based on staged stretching of specimens, as well as heating, cooling and measuring at each deformation stage. This is a time-consuming procedure, and the measurements may not be perfectly accurate. The proposed technique is based on the application of tensile stresses to one standard flat specimen till it fractures followed by processing of the uniform deformation section in the ‘load-travel’ diagram. A number of cross sections was selected in the gauge length of the specimen, and measurements were taken along their width and thickness before and after stretching. By adopting a scale for the ‘load-travel’ diagram, one can determine what the width and the thickness was in the selected cross section of the specimen at any moment of stretching. If one knows what the load was in that moment, one can calculate the material’s resistance to deformation and the strain intensity and thus build a hardening curve. Using the information about how the width and the thickness of the specimen were changing under tension, one can analyse the anisotropy of the material’s mechanical properties and how it developed under strain. To build hardening curves for anisotropic material and to evaluate the developing anisotropy, one needs to analyse specimens cut at 0.45 and 90 degrees to the rolling direction at given temperature and strain rate in isothermal conditions. The proposed experimental technique makes it much easier to determine the mechanical properties of sheet material. And it can be useful for difficult-to-form aluminium and titanium alloys, which find application in aerospace industry and which are deformed under viscoplastic flow conditions.

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