To provide a small peening device capable of correctly limiting a peening range and to provide a reduction method for a residual stress whereby the generation of the residual stress at a welded part is suppressed and reduced.
The peening device has a vibrating terminal (4) installed a carbide material (2) at a tip and an oscillator (6) vibrating the said vibrating terminal mechanically or by a ultrasonic wave, and the said carbide material vibrating hit the surface of a material (8) to be worked repeatedly to reduce the residual stress. In particular, after a welded metal filled on a welding part (12) of the material (8) to be worked is solidified and also before it is completely hardened, this welded part is subjected to peening or hammering to suitably prevent the material to be worked from being damaged by heat shrinkage of the welded metal.
WATANABE MITSUTOSHI
OKABE TADAO
