Abstract
Strain-controlled fatigue tests and tensile tests were performed on four sheet steels in cold-rolled gauges. The fatigue tests involved fully reversed straining cycles. Two dual-phase steels with tensile strengths of 400 (DP400) and 600 MPa (DP600), one HSLA steel (HSLA500) with a tensile strength of 500 MPa and a deep-drawing quality steel (DDQ) were incorporated. The materials were exposed to different pretreatments before testing, such as prestraining in uniaxial tension or equibiaxial stretching or an ageing treatment. The materials often showed cyclic softening during the fatigue tests in as-received condition or after pretreatments. The cyclic stress amplitude at half fatigue life increased in the same order as the tensile strengths of the as-received materials, ie from DDQ, DP400, HSLA500 to DP600. Both prestraining and ageing caused significant increases of the monotonic flow stress. The influence on the cylic stress amplitude was however much smaller. The ranking of the steels with respect to fatigue life was sensitive to the choice of characteristic parameter. When life was plotted as a function of stress amplitude the life fell in the order DP600, HSLA500 and DDQ. The same order was obtained when life was considered as a function of the Neuber factor. However, when life was evaluated vs plastic strain amplitude, the life fell in the order DDQ, DP400, DP600 and HSLA500. Fatigue life was not very sensitive to prestraining and ageing. Both small positive and negative effects on fatigue life could be obtained. A linear relation was found between the fatigue strength at fixed life and the ultimate tensile strength.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
