Study on Microstructure Evolution and Strengthening and Toughening of Friction Stir Processed AA6082-4%Al3Zr In-Situ Composites

A study of friction stir processing experiment of Al3Zr/AA6082 in-situ composites is carried out. The moving speed of the welding tool is 100 mm/min, and the rotating speed of the welding tool is 800, 1000, and 1200 rpm, respectively. The microstructure and mechanical properties of the composites after friction stir processing were analyzed. The results show that Friction stir has a significant effect on the microstructure and strength of composites. Friction stir processing of composite materials promotes the grain refinement of matrix metal and makes the reinforcing particles uniformly dispersed. In addition, with the increase of rotating speed, the reinforced particles are broken and refined under the action of stirring pin. The tensile strength of Al3Zr/6082Al composites processed by friction stir at 1200 rpm reaches 224.139 MPa, which is 45% higher than raw metal. The hardness of stir zone increases with the increase of rotating speed, and the highest hardness can reach 72.1 HV at 1200 rpm.