Influence of Cryogenic cooling (Liquid Nitrogen) on Microstructure and Mechanical properties of Friction stir welded 2014-T6 Aluminum alloy

In this paper, the effect of cryogenic (liquid nitrogen) cooling on grain size and mechanical properties of Friction stir welded (FSWed) 2014 Aluminum alloy was studied. The welding parameters and tool pin profile plays a major role in deciding the weld quality. The threads on the tool profile generates a fairly localized deformation which results high volume of material was stirred and carried with the pin tool and also better mixing of plasticized metal. Cryogenic process (Liquid Nitrogen) was employed after Friction stir welding to reduce the grain size and to improve the mechanical properties of FSWed 2014 Aluminum alloy. It is observed that the grain size is decreased to 250 nm under cryogenic process with the liquid nitrogen by using Transmission electron microscope. It is also observed that mechanical properties are enormously improved. The observed grain size and mechanical properties have been correlated with microstructures and fracture features. (c) 2017 Elsevier Ltd. All rights reserved.