Effect of Ultrasonic‐Assisted Treatment on Microstructure and Mechanical Properties of Laser Deposition Repairing AlSi7Mg Alloy

The study focusing on the repairing technology with highly efficient and high quality for aerospace aluminum alloy parts is of great necessity and application significance. Herein, laser deposition repairing (LDR) technology with and without ultrasonic‐assisted treatment is employed to repair the AlSi7Mg alloy. The morphological analysis results show that ultrasonic‐assisted treatment laser deposition repairing (UT‐LDR) can significantly refine the grain, reduce the porosity, and provide dislocation strengthening of repaired zone (RZ). The microhardness of RZ is higher than that of the base material due to the strengthening effect of fine grain. The microhardness of RZ further increases by 27.7% under the action of ultrasound. With the introduction of ultrasound, tensile strength of repaired samples increases from 180.9 to 241.7 MPa, but the elongation decreases from 4.0% to 1.8%. Both LDR and UT‐LDR samples show brittle fracture mechanism with tiny dimples and obvious cleavage planes.