Patent ID: 8304686

Claim:
A laser shock hardening method for carrying out surface processing of a workpiece in contact with a liquid by irradiating through the liquid the surface of the workpiece with a pulsed laser beam intermittently emitted from a laser irradiation device, the method comprising: setting a velocity of relative movement between the laser beam and the workpiece so that an irradiation interval (dx) of the laser beam defined by a moving distance of the laser spot in a first direction when the laser beam is emitted two times differs from an irradiation interval (dy) in a second direction perpendicular to the first direction; irradiating through the liquid the surface of the workpiece with the pulsed laser beam emitted intermittently from the laser irradiation device, while moving laser spots of the laser beam in the first direction by the irradiation interval (dx) on a processing area of the surface of the workpiece; moving the laser spots of the laser beam in the second direction by the irradiation interval (dy) on the processing area after completion of the move in the first direction; and irradiating through the liquid the surface of the workpiece with the pulsed laser beam emitted intermittently from the laser irradiation device, while moving laser spots of the laser beam in a reverse direction of the first direction by the irradiation interval (dx) on the processing area, thereby shock-hardening the surface of the workpiece.