Effects of Cryogenic Deformation on Second-Phase Al2Cu Particles and Mechanical Properties of 2219 Al–Cu Alloy Rings.

2219 Al–Cu alloy transition rings are widely used in launch vehicles. However, the coarse and agglomerated second-phase Al₂Cu particles significantly deteriorate the mechanical properties and ductility of 2219 Al–Cu alloy rings manufactured by traditional thermal deformation processes. In this study, cryogenic deformation (− 190 °C) is applied for the manufacturing of 2219 Al–Cu alloy rings to alleviate this problem. The effects on the evolution of second-phase Al₂Cu particles and the mechanical properties of the T8-aged samples were examined in comparison with the results of room-temperature (25 °C) and conventional thermal deformation at 480 °C. The results indicate that cryogenic deformation can effectively produce high-density dislocations and strongly crush coarse particles, promoting the dissolution of Al₂Cu particles and improving their distribution in the Al matrix when combined with subsequent solution treatment and rolling processes. As the deformation temperature was decreased from 480 to −190 °C, the area fraction of the coarse particles was decreased from 1.55 to 0.47%, while their mean size was decreased from 11.8 to 8.3 μm. Correspondingly, the uniformity and density of the precipitates after T8 aging were improved. Thus, the mechanical properties of the T8-aged samples were improved with decreasing deformation temperatures; the average ultimate tensile strength, yield strength, and elongation were increased by 20 MPa, 22 MPa, and 3.1% at room temperature. [ABSTRACT FROM AUTHOR]