2. Notion of ductility transition temperature

2.1 Tests on smooth specimens

We consider the case of metals that can fracture by cleavage: face-centered cubics and hexagonal metals, to the exclusion of face-centered cubics. The example most often considered is that of ferritic steels.

The yield strength R _e decreases with increasing temperature T (figure 5 ). At a critical temperature T _c , R _e meets the curve representative of the cleavage stress σ _f . Slightly above this temperature,...