Much of the established data from SENT tests has been generated on ductile materials in the form of tearing resistance curves (R-curves) in terms of J. The testing of SENT specimens is now standardised in BS 8571  and there is potential to use SENTs for high and low temperature tests, but there is little recently published data showing SENT behaviour at low temperature. This paper presents a comparison of fracture toughness data for equivalent SENT and SENB specimens in three different steels as ductile-to-brittle transition curves over a range of temperatures. SENT specimens in comparison to SENBs show higher fracture toughness on the upper shelf, lower transition temperature, but also a much steeper transition from ductile to brittle behaviour. It is therefore important to characterise SENT behaviour at the lowest anticipated service temperatures to ensure that this sudden change in fracture behaviour will be avoided in service.
This paper also describes methods for carrying out SENT tests at very low temperatures, including the use of threaded ends to allow testing inside a temperature controlled test chamber, while preventing the specimen from yielding at locations away from the intended notch tip.