One heat of A 508 steel is investigated in both the unirradiated and the irradiated condition to determine the variation of the fracture toughness with temperature and specimen thickness. C T type specimens with three thicknesses B (12.5, 25 and 50mm) are used. Two fluence levels (3.1019 and 8. 1019 n/cm')(E > I MeV) are investigated. It is shown that the fracture toughness is a decreasing function of both specimen thickness and temperature. A model developed previously by Beremin is used to interpret the results. Axisymmetric notched specimens are tested to determine the factors used in the statistical approach of cleavage fracture. It is confirmed that the Beremin model is able to account for the large scatter in fracture toughness observed at a given temperature on the unirradiated material. The specimen thickness effect is also reasonably well interpreted by the model. The irradiation embrittlement can be explained by assuming that the cleavage fracture resistance is not modified by irradiation and by taking into account only the variations of yield strength with irradiation and test temperature. NOMENCLATURE G, = yield strength eR = stress at failure calculated from equation (1) G~ = cleavage stress (iW = Weibull stress calculated from equation (8) K =stress intensity factor m = Weibull modulus [see equation (7)] V, = characteristic volume f = fracture strain calculated from equation (2) B = specimen thickness N = work hardening exponent K , , and K,, = fracture toughness
A study on the effect of irradiation on the toughness of pressure vessel materials in the ductile regime has been undertaken. Compact tension (CT) specimens of two pressure vessel steels (A533 B and A508 Class 3) and a weld material of fitting chemical composition were irradiated and received neutron fluences of 3 and 8 × 1019 n/cm2. The J-R curves of these materials were determined between 100 and 290°C. Only a very small influence of irradiation was observed for tests at 290°C. In irradiated condition, the effect of the test temperature is not noticeable. At lower temperature, but in the ductile regime, the weld material appears to be more sensitive to neutron irradiation than the two steels. The forged material exhibited a surprisingly high shift of transition temperature since cleavage rupture occurred up to 100°C. A method using tension tests on round notched specimens with different root radii was employed to obtain an alternative value of Jc. This method relates the Jc value to a critical growth of cavities that is determined from the tension test on notched specimens. A good agreement between this method and the conventional one was obtained for the A533 B steel. For the forged material, the results were more questionable and this was attributed to inhomogeneities in the distribution on nonmetallic inclusions for this material. This method is expected to be very useful for the determination of Jc for irradiated materials.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.