Influence of velocity of pressing in RCS processed AA8090 Al-Li alloy

The effect of the velocity of pressing on grain refinement in AA8090 Al-Li alloy sheets during repetitive corrugation and straightening (RCS) at 300 degrees C is studied. V-groove corrugation dies and flattening dies were used at three different pressing velocities of 1.5 mm/s, 2 mm/s and 2.5 mm/s. The specimen temperature was maintained at 300 degrees C. Grain refinement was significantly influenced by the pressing velocity. The samples processed for 8 passes at a pressing velocity of 1.5 mm/s had an improved microhardness value of 104 HV and an increased tensile strength of 405 MPa which is respectively 39% and 113% more than the corresponding values in the parent material. TEM analysis showed that samples processed at a pressing velocity of 1.5 mm/s had in places a grain size down to 50 nm and the EBSD results revealed that the average grain size was 2 pm, with 86% of the total number of grain boundaries of the high angle type.