Experimental Study on Fracture Toughness of Nuclear Graphite

Nuclear graphite is a brittle,polygranular material,which brings difficulties to the research of its fracture toughness.In this paper,an experimental work on measuring the fracture toughness of graphite IG11 is described.Three-point bending tests are employed.The effects of graphite specimen size,thickness,and the relative crack length a/W are studied in the tests.The deformation and stain at the crack tips are also measured.The results indicate that the fracture toughness of IG11 graphite is in a range of 0.82~1.27 MPa·m^1/2.The fracture toughness increases with W of the graphite specimens,but decreases with S of the graphite specimens.The B of the graphite specimens has little effect on the fracture toughness.