MICROSTRUCTURES OF DEFORMATION AND FRACTURE OF CEMENTITE IN PEARLITIC CARBON-STEELS STRAINED AT VARIOUS TEMPERATURES

Internal defects in cementite in a 1. 23% C steel deformed in tension at various temperatures between minus 196 and 700 degree C were studied by transmission electron microscopy. From the extensive report of observations it is concluded that the plastic deformability of cementite increases with an increase in deformation temperature. A remarkably high deformability of cementite above 400 degree C manifests itself clearly both in the strain-induced dislocation structures and in the large dislocation density, which is comparable with that of the ferrite phase.