Feasibility analysis of indentation testing for crack arrest fracture toughness determination

To ensure the safety of in-service pressure vessels, this paper analyzes the feasibility of applying indentation tests for crack arrest fracture toughness predictions, accompanied with highlighting the limitations of conducting destructive fracture toughness tests and the conservatism of applying crack initiation criteria. The role of crack arrest fracture toughness in extending the service life of pressure vessel structures is elaborated. The crack arrest testing methodology specified in ASTM E1221-23 is introduced, and its energy consumption is investigated through the crack initiation and crack propagation. Existing crack initiation fracture toughness prediction models through indentation testing are firstly reviewed. Then, the effects of loading rate and inertial effect on fracture toughness during dynamic crack propagation are analyzed, revealing that increased loading rate may trigger a ductile-to-brittle transition in fracture mode, and the variation of dynamic toughness is closely related to material type and fracture mode. Results confirm that indentation testing enables non-destructive detection using pre-installed irradiation surveillance specimens, thus providing a feasible technical approach for evaluating crack arrest fracture toughness of in-service structures.