A mild steel plate is subjected to constant amplitude uniaxial fatigue loads to produce stresses varying from σmax = 180 MPa to σmin = -40 MPa. The static properties of the steel are σo = 500 MPa, σu = 600 MPa, E = 207 GPa, and Kc = 100 MPa·m^1/2. If the plate contains an initial through-thickness edge crack of 0.5 mm, how many fatigue cycles will be required to break the plate? A = 6.9 x 10^-12 MPa·m^1/2 and n = 3.0. Start by deriving the equation for Nf. For through-thickness edge crack, α = 1.12, and for ferritic-pearlitic steels, A = 6.9 x 10^-12.