Effect of temperature field on microstructural stability of Al–Cu–Mg alloy hemispherical component

Abstract

Al–Cu–Mg alloy hemispherical components can be widely utilized in gyroscope navigation systems by virtue of low density, high deformability and fatigue strength. However, the nonuniformity in residual stress and microstructure of the component after deep drawing may lead to a complex microstructural evolution under the temperature environment, thereby decreasing the navigation precision. In this work, the evolution of grain sizes, dislocations, second phases and mechanical properties of Al–Cu–Mg alloy hemispherical components were evaluated under a temperature field. From the edge to the central part of the component, the grain size first decreased and then increased, while the hardness and residual stress first increased and then decreased. With the extension of exposure time, the dislocation density decreased and the coarsened Al2CuMg phases appeared, while the grain size of the component remained stable. Furthermore, the dislocation density declined faster and Al2CuMg phases precipitated rapider in the die fillet area in comparison with the situation at the bottom of the hemisphere. The higher dislocation density could provide more nucleation sites for Al2CuMg phases. Thereafter, more dislocations were consumed, thus accelerating the reduction of stored energy and lattice distortion under the temperature field. As a result, investigating the microstructural stability and mechanical properties of Al–Cu–Mg alloy hemispherical components can make a contribution to fabricating highly stabilized navigation devices to be further applied in the field of space exploration.