Investigation on hot deformation behavior and quenching precipitation mechanism of 2195 Al-Li alloy

Al-Li alloys suffer from a narrow processing window. The hot deformation behavior of the ramp heating homogenized 2195 Al-Li alloy was investigated by hot compression test in the temperature range of 300–500 °C and strain rate range of 0.01–10 s−1, and the strain compensated Arrhenius constitutive relationship model and processing map of the alloy were established. The laws of Zener-Hollomon parameters on the age-hardening response and quenching sensitivity of the deformed alloy were analyzed. The quenching precipitation mechanism of the deformed alloy were revealed. The results showed that the hardness of the aged alloy tends to increase first and then decrease with increasing Z parameter, while the quenching sensitivity tends to decrease first and then increase. The quench-induced phases are precipitated under the induction of incoherent Al3Zr dispersoids within recrystallized grains. The boundary angle would affect the quenching precipitation behavior. It was also found that the types and amounts of second phases are significantly different between the homogenized and hot-deformed samples under slow cooling rate. The ramp heating homogenized 2195 Al-Li alloy after hot deformation at temperatures of 455–500 °C and strain rates below 1 s−1 possesses a lower flow stress, higher age-hardening response and smaller quenching sensitivity.