Enhanced mechanical and corrosion properties of 2195 Al-Li alloy via cryogenic pre-rolling and aging

Prior to the artificial aging process, the pre-deformation of Al-Li alloy sheets is essential to achieve superior mechanical properties. This study investigates the effects of pre-rolling deformation (3 % similar to 15 %) at room and cryogenic temperature on the mechanical properties, corrosion behavior and microstructure of peak-aged 2195 Al-Li alloy. Cryogenic pre-rolling (CPR) can reduce the peak aging time from 20 h to 8 h. Attributed to the inhibited dynamic recovery, CPR increases dislocation strengthening and promotes heterogeneous nucleation and refinement of T-1 phases. The yield strength of peak-aged CPR samples can be increased from 465 MPa to a maximum of 587 MPa, which is 23 MPa higher than the maximum of room-temperature pre-rolled (RPR) samples. For RPR samples, the average corrosion depth dropped from 84 mu m to 60 mu m, whereas for CPR samples, it further decreased to 54 mu m. The grain boundary precipitation-free zone (PFZ) narrows, which reduces the corrosion electrochemical difference between the matrix and the grain boundary, thereby decreasing the alloy's intergranular corrosion sensitivity. Furthermore, the uniform distribution of fine T-1 phases within the grains increases the impedance modulus, enhancing its corrosion resistance.