Effect of revolutionary pitch on the microhardness drop and tensile properties of friction stir processed 1050 aluminum alloy

Abstract

Friction stir processed (FSPed) aluminum alloys generally exhibit good mechanical properties pertaining to the textural feature, dynamic recrystallization (DRX), aging effect and are commonly accompanied by a thermal mechanical affected zone (TMAZ), and these are important metallurgical factors which cause inhomogeneous deformation problems. Therefore, a 1050 aluminum alloy sheet was used to eliminate the aging effect on the microhardness distribution and tensile properties. From the microhardness profile, a significant data fluctuation variation and microhardness drop could be recognized as the feeding speed slowed to 1.1 mm/s. It is reasonable to suggest that this is closely related to the subtle microstructural changes of dynamic recrystallized grains which were a consequence of the friction stir process heat input. In addition, a significant {110}(001) crystal aggregation was observed in the center of SZs of O-FSPed samples, where (001) aligned closely along the processing direction (PD) while (110) aligned along the transverse direction (TD). The higher Taylor factors of the O-FSPper specimens were responsible for higher flow stress than that of the O-FSPpar specimens. One the other hand, the revolutionary pitch is an insignificant factor for tensile properties. Experimental results imply that FSP possesses great potential to improve the formability especially of cold-rolled H14 tempered sheets, as a partial modification method when a proper feeding speed is properly selected. © 2009 The Japan Institute of Metals.