The S-N data found in BS7608 is based on Stress Range and not Stress Amplitude as used by Fatigue Wizard for material curve data. Fatigue Wizard uses two data points for the derivation of weld S-N curves (see below).
Point (A) corresponds to 0.9xUTS at 1000 cycles and point (B) corresponds to the number of cycles for a stress of 1.0 units.
BS7608 defines a Stress Range curve, typically based on points at 1e5 and 1e7 respectively.
Stress Amplitude is equal to half the Stress Range. Therefore, you can create a modified S-N curve with an identical slope to the BS7608 curve, but offset to account for the Stress Amplitude. You can use the modified curve in subsequent calculations.
