This International Standard specifies methods for determining fracture toughness in terms of K (stressintensity factor), ä (crack tip opening displacement, CTOD) and J (experimental equivalent of the J-integral) for welds in metallic materials.This International Standard is complementary to ISO 12135, which covers all aspects of fracture toughness testing of parent metal and which needs to be used in conjunction with this document. This International Standard describes methods for determining point values of fracture toughness. It should not be considered a way of obtaining a valid R-curve (resistance-to-crack-extension curve). However, the specimen prepara