Process Mechanics in Friction Stir Welding of Magnesium Alloys: Experimental and Numerical Analysis

Abstract

Light weight construction is a major task within automotive and aircraft industry due to lower fuel consumption or increase the possible payload. Structural or exterior shell components are more and more manufactured out of aluminum alloys for this reason. A further weight reduction could be achieved by the substitution of aluminum alloys by magnesium alloys. Also the application of blanks with a varying thickness is a possibility to realize light weight design. To combine the advantages of weight reduction by the use of magnesium alloys and tailored welded blanks (TWBs), an effective joining technique is required. Friction Stir Welding can be used for difficult to be welded magnesium alloys to manufacture magnesium TWBs. During this process the different thickness of the two sheets can cause an unequal heat distribution below the tool, affecting material flow and therefore components strength. In the paper the main results of a numerical and experimental campaign on Friction Stir Welding of AZ31 magnesium alloy tailored blanks are presented. The numerical simulation was validated by experimental observations and the occurring bonding conditions have been analyzed in both approaches.