BS 8571:2018

This British Standard gives methods for determining fracture toughness in metallic materials in terms of δ (crack tip opening displacement, CTOD) and J (experimental equivalent of the J-integral) using single edge notched tension (SENT) specimens.

This British Standard also gives a method for determining fracture toughness as a resistance to ductile crack extension (R-curve), or single point determination of fracture toughness at onset of unstable crack extension, or pop-in. The method uses specimens which have been notched and fatigue pre-cracked into parent metal, weld metal or heat affected zone (HAZ). The specimens are loaded in tension, and the force and crack mouth opening displacement are recorded.

NOTE Methods to evaluate the suitability of a weld for notch placement within the target area and, where appropriate, to evaluate the effectiveness of the fatigue crack in sampling these areas are given in BSENISO15653.