Evaluation of the Structural Characteristics and Wear Performance of the Novel ECAR-Processed AA5083 Alloy

Commercially available AA 5083 alloy was processed by a novel equi-channel angular rolling (ECAR) using copper shielding on either side of the alloy sheet. ECAR processing was performed for four passes with different die channel angles (90°, 105° and 120°) with and without copper shielding. Vickers hardness was determined and observed that the hardness was increased by 150% for the alloy with 1-mm-thick copper shielding processed through 90° channel angle dies. Increased sliding distance resulted in less specific wear, which may have been caused by strain hardening. The less wear rate was observed for the alloy processed with 1-mm-thick copper shield. The results of the FE-SEM investigations revealed that the primary wear mechanism for the unprocessed alloy was "adhesive" and "abrasive" for the processed alloy. The (h k l) values were determined to be (111), (200), (220), (311) and (222) and were matched with aluminum. For the alloy processed with copper shielding, the interlamellar spacing (d) decreased with the number of passes and the crystal size reduced from 104 to 35 nm. The coefficient of friction (COF) between steel die and copper is much lower than that between aluminum and steel die, and hence, the novel method of using copper shielding during the ECAR process improved the wear resistance and reduced the crystallite size due to which the hardness was enhanced significantly.