This paper deals with the fundamental study on the plastic deformation of the metal plate by using the water hammering of high-speed water jet. This water jet was spouted out from an orifice of a vessel in which an impulsive high current discharge was generated.
The following conclusions are obtained;
(1) The water jet consists of three parts in which the main part is central water jet which has uniform motion with the maximum velocity about 260m/s. The spouted length of the jet decreased as the diameter of the orifice became larger and the length of the parallel part was longer.
(2) The depth of the plastic deformation by the high-speed water jet was changed according to the nozzle diameter. It became clear that there was most suitable nozzle diameter on the maximum deformation.
Moreover, there was adequate parallel part as the depth of deformation became maximum. The parallel part was attached to the end of the conical vessel.