‘Twinning’ and Fracture in Chromium

Abstract

Two types of brittle-to-ductile transition in tension have been found in chromium. In the annealed condition chromium is brittle at relatively elevated temperatures and low stresses in the strain-ageing region^1,2, while in the warm-worked condition² or after alloying, a transition occurs more typical of other body-centred cubic metals, at low temperature and high stresses³. Explanations of the high-temperature brittleness follow well-known models of dislocation locking⁴ or modifications involving fine precipitates²; however, these mechanisms do not wholly explain either the abrupt nature of the transition or the low stresses at which it occurs.