BS 8571:2018 pdf download

BS 8571:2018 pdf download.Method of test for determination of fracture toughness in metallic materials using single edge notched tension (SENT) specimens
1 Scope
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 BS EN ISO 15653.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
BS EN ISO 15653:2018, Metallic materials — Method of test for the determination of quasistatic fracture toughness of welds
ISO 12135:2016, Metallic materials — Unified method of test for the determination of quasistatic fracture toughness
3 Terms, definitions and symbols
For the purposes of this British Standard, the following terms, definitions and symbols, and those given in BS EN ISO 15653 and ISO 12135, apply.
3.1 Terms and definitions
3.1.1 blunting
increase in crack length not associated with the creation of new fracture surface prior to the onset of unstable crack extension, pop-in or slow stable crack extension, and occurring within the same plane as the fatigue pre-crack
3.1.2 pop-in
abrupt discontinuity in the force versus displacement record, indicated by a sudden increase in displacement and, generally, a sudden decrease in force, subsequent to which displacement and force increase to above their previous values
3.1.3 sample
un-notched blank cut from the source material
3.1.4 specimen
machined and notched sample ready for testing
3.1.5 target area
intended fatigue pre-crack tip position within the parent metal, weld metal or heat affected zone (HAZ)