Accession Number : AD0478590

Title :   THE DEFORMATION AND FRACTURE OF MILD STEEL CHARPY SPECIMENS.

Descriptive Note : Technical rept.,

Corporate Author : STANFORD UNIV CA DEPT OF MATERIALS SCIENCE AND ENGINEERING

Personal Author(s) : Wilshaw, T. R.

Report Date : JAN 1966

Pagination or Media Count : 38

Abstract : A qualitative analysis of the deformation mechanism of mild steel Charpy specimens in slow three-point bending is deduced from observations of plastic strain patterns revealed by Fry's reagent, and also geometrical changes in shape. The plastic strains around the notch are measured using a micro-hardness technique and related to the distance below the notch root and the angle of bend. From this the plastic strain rates around the notch root are related to the striker velocity. The effect of strain hardening on the stress distribution below the notch is determined quantitatively and an equation of state is derived to describe the conditions for cleavage fracture beyond general yield. Above general yield there is a sharp increase in the fracture load and ductility associated with a transition in the mode of fracture initiation from ductile cleavage to ductile shear. This transition is discussed in terms of the deformation mechanics and a reason for the shapes of Charpy impact energy curves is suggested. (Author)

Descriptors :   (*STEEL, MECHANICAL PROPERTIES), DEFORMATION, FRACTURE(MECHANICS), STRAIN HARDENING, HARDNESS, NOTCH SENSITIVITY, PLASTIC PROPERTIES, STRAIN(MECHANICS), LOADS(FORCES), IMPACT TESTS.

Subject Categories : Metallurgy and Metallography
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE