Mathematical model development for superplastic forming of sheet shells by subliming agent gas pressure

Abstract

The authors presented in the article an analytical model of superplastic forming of spherical shells by pressure of the gas (gaseous phase) created upon sublimation of sublimate agent. Sublimate was placed in a hermetic cavity between the workpiece and the presser cover and heated to the temperature of its sublimation. The model uses the Berthelot equation for the state of real gases, the Bernoulli relation, and the F. Jovane equations for adjusting the shell forming pressure as a function of its relative height, the heat balance equation for the sublimation process, and the Clausius-Clapeyron relation for sublimation of substances. The authors showed that the superplastic forming pressure control can be effectively applied by the way of change in the forming temperature relative to temperature of sublimate agent sublimation. The experimental results of forming of shells from aluminum alloys AlMg3Mn, AlMg5Mn and AlMg6Mn, confirming theoretical calculations of the velocity and temperature conditions of superplastic forming by the sublimating agent pressure.