On the possibility of avoiding the use of a clip-gage when testing PCCv specimens in the ductile-to-brittle transition region

Fracture toughness testing using bend-type samples, such as precracked Charpy specimens, requires using a clip-gage for measuring crack mouth opening displacement (CMOD). This paper demonstrates that it is possible to avoid using a clip-gage and use machine crosshead displacement (MCD) as an approximation of load-line displacement; this simplifies considerably the test procedure, both in terms of mechanical operations and specimen instrumentation. This is particularly desirable for irradiated materials and when testing sub-size specimens. Results obtained in the ductile-to-brittle transition regime from the analysis of 151 toughness tests show that reference temperatures calculated using the Master Curve methodology with CMOD and MCD are fully equivalent within a few degrees. The investigation has been conducted on different materials, test machines, full-size and sub-size specimens.