Compliance Correction for Determining Load-Line Energies for Compact Fracture Toughness Specimens

A compliance correction technique has been used to calculate energies in the compact specimen test measured at the specimen loading line using the machine ram displacement. The compliance-corrected results for nine pressure vessel steels tested at temperatures of room temperature, 71°C, and 177°C have been compared with the direct measurement (standard clip gage) approach, and the results show essentially a 1:1 relationship with a correlation coefficient of 0.997. This technique should be useful for determining elevated temperature, ductile fracture toughness values and for tests in which the normal clip gage (or other technique) fails to operate.