Patent ID: 7399371
Filing Date: 2008-07-15
Classification: C21D,G01N

Abstract:
1. A treatment method for improving fatigue life of a metal material characterized by comprising the steps of; for portions of the metal material for which fatigue may become a problem: (a) detecting a crack for the portions to be subjected to the ultrasonic impact treatment by liquid penetrant examination, magnetic particle examination or eddy current examination; (b) if a crack is detected, removing the crack by a grinder or by gouging; (c) if a removal depth is as deep as 5 mm or greater, repairing the removal portion by buildup welding; (d) then performing ultrasonic impact treatment; and then (e) confirming that a curved surface having depth of 0.05 mm or greater and a radius curvature of about 0.5 mm to 3 mm is formed at the ultrasonic impact treated surface.