Evaluation of the Short Rod Method for Measuring the Fracture Toughness of Beryllium

摘要

The fracture toughness of CIP/HIP-1 beryllium was measured by testing five compact toughness (CT) specimens, following the ASTM E 399 method except for using KF in fatigue pre-cracking of about 0.8 KIc as opposed to the 0.6 KIc required by E 399 (beryllium is very difficult to fatigue pre-crack). The CT measurements agreed very well with previous measurements of the toughness of beryllium. The tested CT specimen halves were then machined into short rod specimens, and the fracture toughness was measured by the short rod method. The average of the short rod measurements differed from the average CT measurements by about 2 percent. In addition, the short rod tests provided a measure of KIa, the stress intensity factor which allows a fast-moving crack to arrest. These results, together with the simplicity of the short rod test in which no fatigue pre-cracking is required, make the short rod method attractive for measuring the fracture toughness of beryllium. (Author)