When a literature search and discussion with manufacturers revealed that there was virtually no existing data related to the fracture properties and behavior of copper beryllium alloy C17510, a series of test programs was undertaken to ascertain this information for several variations in material processing and chemistry. These variations in C17510 were primarily optimized for combinations of strength and conductivity. While originally intended for use as cyclically loaded high-field, high-strength conductors in fusion energy research, material testing of C17510 has indicated that it is an attractive and economical alternative for a host of other structural, mechanical, and electrical applications.
ASTM tests performed on three variations of C17510 alloys included both J-integral and plane strain fracture toughness testing (E 813, E 399) and fatigue crack growth rate tests (E 647), as well as verifying tensile, hardness, Charpy, and other well-defined mechanical properties. Fracture testing was performed at both room and liquid nitrogen temperatures, which bound the thermal environment anticipated for the fusion components being designed. Fatigue crack propagation stress ratios ranged from nominal zero to minus one at each temperature. In order to confirm the test results, duplicate and independent test programs were awarded to separate facilities with appropriate test experience, whenever possible.
The primary goal of the test program, to determine and bound the fracture toughness and Paris constants for C17510, was accomplished. In addition, a wealth of information was accumulated pertaining to crack growth characteristics, effects of directionality, and potential testing pitfalls. The paper discusses the test program and its findings in detail.