Zwick has expanded its metals testing programme to include two standardised Pellini drop weight testers rated at 550j (Type P550) and 1630j (TypeP1630).
The 550 joule drop weight tester is used for Pellini drop weight tests on metallic materials with specimen dimensions to P2, P3 and P4.
The drop height is adjustable up to a maximum of 1000mm and tooling for the various specimens can be easily changed.
The prescribed drop energies are obtained by using weights, with the drop energy calculated automatically.
The Pellini testers feature a safety arrangement that prevents access to the test area during test mode.
The Pellini drop weight test investigates the tendency of ferritic steels to brittle fracture and crack arrest behaviour.
In this test, rectangular flexure specimens are loaded with a free-falling mass so that a brittle fracture is caused on the tension side of the specimen within a prescribed total deflection.
This brittle fracture is caused by a notched welding bead laid on this side, called the crack starter.
The prescribed flexure is limited with suitable stops.
It is necessary to determine whether the brittle fracture caused by the artificial crack-starter spreads as far as one of the two side faces of the specimen or if it is arrested beforehand.
If the fracture reaches one of the side faces, the specimen is regarded as fractured.
The highest temperature at which the specimen breaks, when at a stated higher temperature two further specimens of the same material do not break, is described as the NDT temperature and represents a characteristic value for the crack arrest behaviour of the material under test conditions.
The NDT (nil ductility transition) temperature describes the transition temperature for crack arrest as determined in the Pellini drop weight test.
