METHOD FOR ENHANCING FATIGUE STRENGTH OF SPOT WELDED JOINT BY ULTRASONIC SHOCK TREATMENT

摘要

PPROBLEM TO BE SOLVED: To provide a treating method for enhancing fatigue strength of welded joint while ensuring good workability in a spot welded joint of metal sheet, particularly in the spot welded joint of high strength steel sheet. PSOLUTION: In the method for enhancing the fatigue strength of the welded joint formed by spot welding the metal sheet (the high strength steel sheet), ultrasonic shock treatment is applied to one or both of a nugget portion and a portion around the nugget from both surface or one surface of the welded joint. PCOPYRIGHT: (C)2004,JPO