hexagonal close-packed metals are tested over a relatively wide temperature range, they tend to deform plastically by a combination of slip along glide planes and twinning in discrete zones within the specimentwinning occurs, extension of the gage length proceeds in discrete bursts that are associated with twin band nucleation and growth.A similar stress–strain response is found in body-centered-cubic metals tested at low temperatures and in face centered-cubic metals tested under a combination of low temperatures and high strain rates