Mechanisms and microstructures of 2A97 Al-Li alloy under the hot forming with synchronous quenching process

Aluminum-lithium alloy is regarded as the most promising light material in the aircraft and aerospace industries. For the production of complex and high-precision parts, the hot forming with synchronous quenching (HFSQ) process has become an effective and attractive forming method. In order to achieve the performance and microstructure evolution of the 2A97 Al-Li alloy under the HFSQ process, the specimens were subjected to solution treatment at 520°C and held at 90 min in the Gleeble 3,500 thermal simulator. Then the hot tensile test with simultaneous quenching was conducted directly at a temperature of 300-500°C and a strain rate of 0.1-0.001 s^-1 with the same equipment. Through analyzing the macroscopic stress-strain curves and microscopic fractures, it was concluded that the optimal forming temperature was 450°C with the strain rate being 0.1 s^-1 and its forming mechanism under the process was presented. To obtain the microstructure evolution of 2A97 Al-Li alloy under the HFSQ process, the material was subjected to constant strain tensile test with synchronous quenching and then treated with two-stage artificial aging 200°C and 6 hr + 165°C and 6 hr. The microstructure of the alloy was observed by means of electron backscattering diffraction (EBSD). And its evolution process and the influence of temperature, strain rate, and strain on the microstructure under the process were attained.