The relationship between notched bar impact bending test, Robertson test and drop-weight test

The temperature of the Robertson-Test referred to as crack-arrest-temperature determines the change of the fracture mode from brittle to tough. It was found out that for 22 NiMoCr 37 (similar to A 508 Cl 2) and St 37 steels this temperature was corresponding with the upper shelf temperature of the impact test. This is also the temperature at which there cannot be initiated any cleavage fracture (fracture transition characteristic temperature) in the modified drop-weight-test, and it is corresponding with the FTE-point for large wall thickness in the FAD by Pellini which is also 65-70 K above NDT. Thick walled components as well can be considered at this temperature to be absolutely safe in terms of brittle fracture, if possibly generated brittle areas of base of HAZ material will remain localized in small isolated volumina. The latter requirement has to be verified by adequate manufacturing. (Auth.)