The ASTM Crack-Arrest Test, which is under development, is generally limited to providing data up to 20 to 40°C above the ductile-to-brittle transition temperature (expressed as RT_NDT in the ASME Boiler and Pressure Vessel Code). For this test, the geometry is a wedgeloaded compact specimen containing a brittle weld starting notch, which appears incapable of reliably generating a rapid crack above the stated temperature range.

Two alternatives have been used for obtaining data at higher temperatures: very large specimens combined with soft loading systems and modified compact specimens. This paper describes compact-specimen modifications which have extended the successful temperature range to the onset of the Charpy upper shelf, the highest relative temperature reached being RT_NDT + 100°C.

Specific modifications utilized are: a high-strength steel crack-starter section (duplex specimen), a low-friction loading arrangement (inverted split pins), and contoured side grooves. The high-temperature data generated using these modifications compare favorably with largespecimen results.