On microstructure, hardness, and fatigue properties of friction stir-welded AM60 cast magnesium alloy

Friction stir welding, as a solid-state joining method, seems a viable joining/assembly method for difficult-to-weld cast magnesium alloys. Due to the high flammability of Mg alloys, fusion-based welding techniques may not be successful to join Mg made component. Therefore, a solid-state operation can be considered as an effective method to join so-called unweldable Mg alloys. For doing so, friction stir welding, as one of the most common solid-state joining and processing methods, has been extensively studied for similar/dissimilar welding of different grades of magnesium alloys. In the present study, we aim at studying the effect of the friction stir welding parameters on mechanical performance, fatigue properties, and microstructure of one of the little-studied cast Mg alloys, AM60. To this end, different parameters including tool rotational speeds and transverse speeds (feed rate, mm/min) were tested on the AM60 Mg sheets to find the conditions that provide defect-free welds. Then, microstructural, mechanical, and fatigue characterizations were assessed on the as-welded specimens to demonstrate microstructure/properties (fatigue performance and strength properties)/process parameters correlations.