G0301503 Effect of pre-strain on the fatigue strength of the thin steel plate for automobile

Abstract

Society of Automotive Engineers of Japan (JSAE) tested fatigue strength by shear fatigue test for mild steel, JSC270C, and high tension steel, JSC590Y, joined by rivets. As the result of the tests, fatigue strength was independent of the strength of base materials. JSAE reported pre-strain of the rivet affect the fatigue strength.This study investigates fatigue test method of cold rolled steel sheet and estimates material dependence of pre-strain on fatigue strength. We conducted fatigue test for virgin and pre-strained materials. Pre-strain was given to specimen by bending. Pre-strain levels were evaluated by hardness test. Cracks from both sides of the specimen have developed. Many cracks were initiated on the specimen surface and grown with coalescences. It was unlikely to have storong effect of pre-strain on the fatigue strength.