AbstractSurface crack growth has been studied in centre notched and smooth panels of low carbon steel under symmetric axial elastic‐plastic cyclic straining. The crack shape, followed by heat tinting, has been found to be approximately semi‐circular for crack radii 0.3–5 mm. Both smooth and notched specimens have been fatigued until fracture. The smallest notches of 0.1 mm in radius and depth approximately represent defects of a critical size under present loading conditions. Crack propagation rates have been measured and plotted vs ΔJ. Both present part through‐crack data and previous long through‐crack data in the elastic and the elastic‐plastic regions are compatible. A single dependence of dl/dNvs