Accession Number : AD0757042

Title :   A Constitutive Relation for Deformation Twinning in Body Centered Cubic Metals.

Descriptive Note : Technical rept.,

Corporate Author : MARYLAND UNIV COLLEGE PARK ENGINEERING MATERIALS GROUP

Personal Author(s) : Armstrong,Ronald W. ; Worthington,Peter J.

Report Date : JAN 1973

Pagination or Media Count : 17

Abstract : A constitutive relation is developed to describe the grain size, temperature and strain rate dependence of the stress required for the essentially elastic twinning of body centered cubic (bcc) metals at low temperatures. The relation is derived from a description of the bulk material strain produced by twinning and, also, from specifying on the basis of a thermal activation analysis the number of twins and the twinning nucleation rate. Two natural consequences of this development for bcc metals are that twins must be nucleated by pre-twinning slip and that twinning and brittle fracture are predicted to occur under very similar circumstances. These are normal experimental observations. (Author)

Descriptors :   (*TWINNING(CRYSTALLOGRAPHY), METALS), (*STEEL, DEFORMATION), CRYOGENICS, SHEAR STRESSES, STRAIN(MECHANICS), GRAIN STRUCTURES(METALLURGY), GRAIN SIZE, NUCLEATION, PHASE STUDIES, MICROSTRUCTURE, FRACTURE(MECHANICS)

Subject Categories : Properties of Metals and Alloys
      Crystallography
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE