A data base of the fatigue crack growth for nuclear component ferritic steels was constructed. Data collected are of the low alloy steels (A533B-1, A508-2, A508-3) and a carbon steel (STS42) tested in air from room temperature up to 371°C. Characterization of the fatigue crack growth data and improvement of the conventional design curve were attempted. A proposed design curve is given as follows ; da/dN = 3.57×l0-9{(1 + 0.30R)(E0/E)0.51ΔK}3.02 (da/dN : mm/cycle, ΔK : MPa√(m)), where da/dN is the fatigue crack growth rate, R is the stress ratio, E0 is the Young's modulus at RT, E is the Young's modulus at the temperature concerned and AK is the stress intensity factor range. This equation proved better applicability than the one proposed in ASME.
