Experiments on the transferability of fatigue crack growth data at temperatures above 700°C

Fracture mechanics methods are used for the safety assessment of reactor components at temperatures up to 500 °C. For the high temperature region above 700 °C to date fracture mechanics is in the stage of laboratory tests. In the German P roject N uclear P rocess Heat (PNP), fatigue crack growth data are required. Some experiments have been performed with CT-specimens e. g. by Kwasny (1987) and by Huthmann (1985). But the questions arises, if the data gained with these standard specimens can be considered as characteristic material parameters and can be used as a basis for design. To get information on this topic, fatigue crack growth experiments have been performed with several specimen types and sizes respectively. For the material X 10 NiCrAlTi 32 20 (Alloy 800 H) three standard specimen types (CT 1”, CT 1/2”, CCP 1/2”) and tubes with external circumferential cracks were used. For the nickel base alloy NiCr 22 Co 12 Mo (INCONEL 617) experiments were performed with two sizes of CT-specimens (CT 1”, CT 1/2”).