Relation of fracture toughness and tensile plastisity in some hi strength condition.

The states of brittleness are inherent in almost all metallic materials and is the ultimate state limiting its use in constructions. The brittleness of the material is the state in which the material is destroyed without significant plastic deformation. Brittleness has pursued materials almost since their discovery in ancient times, since unsuccessful attempts at doping or deformation or heat treatment led to the destruction of the material with the slightest deformation during operation. At about the same time, a method for controlling brittleness appeared –deformation the material to plastic state.

Significantly later, only at the beginning of the 20th century (Grififits, Irvin), another criterion of material performance in the presence of internal and external stress concentrators in the structure was formulated - fracture toughness. Accordingly, the state of the constructions, in which stress intensity factors appear in material above the level of fracture toughness, is called constructions fragility.

In this work, states with very low tensile elongation and the ratio of the fracture toughness of various titanium alloys are considered. It is shown that brittleness can be achieved with practically any type of structure, if there is a sufficient number of fine hardening phases or the corresponding state of interphase boundaries. The ratio of fracture toughness and tensile ductility significantly varies depending on the state and type of structure.