Friction Stir Processing of Aluminum Alloy A206: Part II—Tensile and Fatigue Properties

The impact of friction stir processing (FSP) on the structure and mechanical properties of the age-hardenable aluminum casting alloy A206 was investigated. FSP nearly eliminated the solidification shrinkage porosity present in the as-cast condition. FSP significantly increased both the strength and tensile ductility of cast A206 alloy. When applied to A206 that had previously been solution-heat-treated and aged, FSP resulted in a more moderate increase in strength; however, ductility was notably increased. A206 that had been subjected to FSP was found to respond to artificial aging treatment. Fatigue resistance was also found to be significantly enhanced in A206 after FSP. The entire S–N curve is favorably shifted after FSP, and more importantly, fatigue strength at 108 cycles nearly doubled from about 85.5 MPa in the as-cast condition to 165 MPa. These results point to FSP as an effective way to locally enhance the mechanical properties of cast Al components.