Abstract:This study performs single point incremental forming (SPIF) on two aluminum alloys (i.e. AA5754 and AA6061), and analyzes their post forming mechanical properties and microstructure evolution. The forming parameters namely wall angle (35°-55°), feed rate (1-4 m/min), spindle rotational speed (50-1000 r/min), and lubricant (grease and hydraulic oil) are varied to probe detailed processing effects. The pre- and post-SPIF mechanical properties and microstructures are characterized by conducting tensile tests and optical microscopy, respectively. It is shown that an increase in the wall angle, feed rate and rotational speed causes microscopic variations in the alloys such that the grains of AA5754 and the second phase particles of AA6061 elongate. As a result, the ultimate tensile strength of the formed parts is increased by 10% for AA5754 and by 8% for AA6061. And, the ductility of AA5754 is decreased from 22.9% to 12% and that of AA6061 is decreased from 16% to 10.7%. Regarding the lubricant effect, it is shown that the mechanical properties remain insensitive to the type of lubricant employed. These results indicate that SPIF processing modifies the microstructure of Al alloys in a way to enhance the strength at the cost of ductility.

Key words: single point incremental forming; mechanical properties; microstructure evolution; aluminum alloy; wall angle; forming parameter