Book Description

The origins and rationale for the three plane-strain fracture toughnesses defined by the new ASTM Test Method for Plane-Strain (Chevron-Notch) Fracture Toughness of Metallic Materials (E 1304-89) are reviewed. KIvM represents the toughness measured in a greatly simplified test, but it can be less accurate than KIv and KIvj. The test for KIv is complete with all the procedures and validity criteria necessary to assure accurate measurements of plane-strain critical stress-intensity factors. When a material exhibits a crack-jump behavior, the KIv procedure must be modified, and the toughness is called KIvj. This paper suggests that ASTM E 1304-89 toughness measurements can be used for the full range of applications appropriate to KIc values measured by the ASTM Test Method for Plane-Strain Fracture Toughness of Metallic Materials (E 399-83). However, a material-dependent constant, equal to about three times the ctack-tip plastic zone radius, should be added to the preexisting flaw size in calculations of crack stability.