MECHANICAL BEHAVIORS AND DEFORMATION CONTROL OF AS-QUENCHED Al-Cu ALLOY FOR LARGE AEROSPACE STRUCTURES

摘要

Excessive deformation in quenching is one of major problems in the integrated manufacturing process of large aerospace structures. In this paper, the mechanical properties during quenching were studied for the high-strength cast Al-Cu alloy, and the difference on flow stress was found between high-temperature and low-temperature cooling stages. The Arrhenius constitutive model was proposed to evaluate the effect of temperature. A thermo-mechanical simulation was conducted with the consideration of cooling sequence and clamping fixture. The reason on quenching deformation was concluded that the deformation energy was transformed into plastic strain in high-temperature stage under the constraint of the fixture, while it was converted into elastic energy with the increase of the material strength in low-temperature stage which was released as a springback. The new process design was proposed and the distortion was well controlled from 8mm to 2mm.