Not necssarily. It depends on the SN curve. DesignLife does not use the yield stress in SN fatigue. It uses the calculated alternating stress and the SN curve to predict the fatigue damage/life. See the SN curve below for basic structural steel from Engineering Data. Its YS is 250 MPa, which correlates to a N of about 12,000 cycles. So, an alternating stress slightly greater than 250 MPa will predict more than 10,000 allowable cycles. For other materials, the spread maybe larger.  What is the N value on your SN curve for 480 MPa?
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