Study on the Effect of Pre-strain on Fatigue Properties of Dual-phase Steel

Abstract

Abstract The uniaxial tensile test investigated the fatigue performance of DP780 steel without pre-strain and with 5% and 10% uniaxial pre-strain. Topography of fractured surfaces was observed to study the relationship between pre-strain and fatigue performance. The results showed that pre-strain the specimens would affect the fatigue performance of DP780 steel. It would cause an increase in fatigue life when the stress was comparatively high and the fatigue life was less than 100,000 cycles. However, the fatigue life was reduced when the stress level was comparatively low, and the fatigue life was more than 100,000 cycles. Pre-strain reduced the fatigue strength of samples. Fatigue strength of specimens without pre-strain and 5% and 10% pre-strain were 318 MPa, 310 MPa, and 303 MPa, respectively. The sample fracture was a brittle fracture with a pre-strain of 5%, while it was a ductile fracture with a pre-strain of 10%.