Fracture testing of beryllium copper alloy C17510

Beryllium-copper alloy C17510 has been selected as the primary candidate material for the Burning Plasma Experiment (BPX) toroidal field (TF) coil conductors. Since the coils will be subjected to both mechanical and thermal load cycling during their design life, it becomes imperative to be able to predict the fatigue crack propagation characteristics of this structural system. While C17510 is well defined in terms of conventional static properties, virtually no data existed for its plane-strain fracture toughness and fatigue crack growth rate constants, but are required if an accurate life prediction of the coils is to be made using linear elastic fracture mechanics. As a result, a test program was implemented that determined fracture constants for two different variants of the C17510 alloy at both room and liquid nitrogen (77 K) temperatures, the thermal bounds of BPX TF operation. The authors discuss the test program, in particular, fracture toughness and fatigue crack propagation testing, and their respective results