Experimental investigation of cooling medium on submerged friction stir processed AZ31 magnesium alloy

Abstract Submerged Friction stir processing (SFSP) has become apparent as a technique to modify microstructure. It is used to generate refined grains, modify microstructure, achieve superplasticity, synthesize insitu composite and form intermetallic compounds. In this work, AZ31magnesium alloy is friction stir processed at different rotational and welding speed while submerged underwater, cooling oil and brine solution. The effects of different medium on tensile strength, percentage of elongation, hardness, average size of grains in submerged friction stir processed magnesium alloy samples are discussed and the final results are compared. This investigation produces evidence that submerged friction stir processing under coolant oil results in lower peak temperature. During SFSP, water cooling resulted in lower tensile strength when compared to brine solution and coolant oil.