Size effects and energy disposition in impact-specimen testing of ASTM A 533 grade B steel
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A series of impact-type specimens, ranging in thickness from 0.1 to 12 in., have been tested. The effects of size on the impact energy per unit volume of the plastically deformed material of the specimens tested are investigated using the laws of similitude. Complementary to this, a model illustrating the disposition of energy between shear lip and flat fracture is proposed and satisfactorily verified by the test results. It is shown that significant size effects on impact energy exist at all temperatures and, in particular, a size effect of around five exists even at upper-shelf temperature for 12-in.-thick impact specimens when compared to the energy from thinner specimens, say a Charpy impact specimen. This is to say that, on the upper shelf, the impact energy of a 12-in.-thick specimen is equivalent to between 25 and 30 ft-lb Charpy impact energy. To lend further support to the behavior thus defined, it is shown that the nil-ductility type behavior in 12-in. thicknesses is exhibited at around 145° F as compared to the similar behavior exhibited by regular drop-weight specimens at around 0° F. That is, the nil-ductility temperature, if redefined as a type of behavior and not confined to a given size specimen for 12-in.-thick plate, is about 145° F.
KeywordsMechanical Engineer Fluid Dynamics Unit Volume Impact Energy Type Behavior
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