Nano-Sized Grain Refinement Using Friction Stir Processing

Report No. ARL-RP-422
Authors: Brian Thompson, Kevin Doherty, Jianqing Su; Rajiv Mishra
Date/Pages: March 2013; 16 pages
Abstract: A key characteristic of a friction stir weld is a very fine grain microstructure produced as a result of dynamic recrystallization. The friction stir processing (FSP) technique was applied to modify the through thickness microstructure of a monolithic plate of a magnesium alloy. Grain structure refinement in these alloys could have a significant impact on their strength and ductility opening up their use for high-performance defense applications. EWI has been investigating the use of the FSP technique to achieve nano-sized grains in a magnesium alloy, AZ31B. Heat input estimations have enabled the prediction of welding parameters and tool geometries that could achieve significant grain refinement. This presentation will summarize the experimental procedures using active cooling and theoretical efforts undertaken in order to achieve an average stir zone grain size of 500 nm. This work was performed under a cooperative agreement between EWI and the U.S. Army Research Laboratory.
Distribution: Approved for public release
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Last Update / Reviewed: March 1, 2013