Investigation of the Ductile-Brittle Transition for Certain BCC and HCP Metals.

The general purpose of this research program has been two-fold 1 to determine the brittle fracture characteristics, mainly, of several steel and titanium materials and, 2 to develop via appropriate constitutive relations a detailed description of the ductile-brittle transition behaviour which is exhibited by certain BCC and HCP metals. The brittle fracture behaviour of these materials was directly measured by tensile testing at 4.2K. Compression tests at 4.2K were performed, also, so as to establish the nature of whatever plastic deformation behaviour might be induced in the absence of applied tensile stresses.