THE EFFECT OF METAL ALLOY MICROSTRUCTURE ON THE THICKNESS DISTRIBUTION IN THE CIRCULAR PLATE UNDER THE SUPERPLASTIC BLOW-FORMING

The gas-blow forming of sheet specimens under the superplastic conditions is the widespread and intensive developing technological method for metal-forming of modern alloys (mainly on the aluminium and titanium base). The investigation of evolution of the microstructure parameters in the deformation process is necessary to obtain the defect-free constructions with required mechanical properties. In thepresent paper the blow-forming process of the thin circular plate to the hemispherical form is modelled. The stress-strain relations used include the parameters of the grain size and of the hardening depending on theaccumulated plastic strain. It is shown that taking into account the evolution of the microstructure parameters in the superplastic deformation can significantly improve the estimation of the optimal characteristics of the manufacturing process and eventually can provide the most thickness-uniform engineering product.