Welding method

The invention provides a welding method. In the whole process that a workpiece is welded by a welding gun, an ultrasonic wave impact device aims at high-temperature weld metal which is solidified on the workpiece and does not recover strength to carry out ultrasonic wave impact; in such a way, the ultrasonic wave impact device and a welding gun body synchronously move in a companying way; during welding, the impact in ultrasonic frequency is applied to the high-temperature weld metal which is solidified on a certain position behind a molten bath and does not recover strength along the thickness direction of a workpiece to be welded; the metal in a condensation shrinkage state is impacted to produce ductile extension under the exciting force effect of ultrasonic wave; compressed plastic strain produced in the heating process is compensated, so as to reduce the welding deformation; the texture of the weld metal is refined, the directivity of crystalline grain crystallization is changed, and the texture tends to