ASTM International

An Introduction to the Development and Use of the MASTER CURVE METHOD
 N MNL52

Annotation

THE PRESENT MANUAL IS WR1TTEN AS EDUCATIONAL MATERIAL FOR non-specialists in the field of fracture mechanics. The intention is to introduce a concept that can be understood and used by engineers who have had limited exposure to elastic-plastic fracture mechanics and/or advanced statistical methods. Such subjects are covered in detail in USNRC NUREG/CR-5504 [1].

Section 2 explains why the application of fracture mechanics to ordinary structural steels has been delayed for so long. Underlying the explanation is a problem with a technical subject matter that has become, to a degree, unnecessarily esoteric in nature. The Master Curve method, on the other hand, addresses the practical design related problem of defining the ductile to brittle fracture transition temperature of structural steels directly in terms of fracture mechanics data. Section 2 describes the evolution of the method from a discovery phase to the development of a technology that can be put to practical engineering use (see Note 1).

Note 1--Section 2 denotes stress intensity factors as Kic or Kjc. The former implies linear elastic and the latter elastic-plastic stress intensity factor properties. KIc also implies that larger specimens had to be used.

Section 3 explains the data validity requirements imposed on test data and the number of data required to constitute a statistically useable data set for determining a reference temperature, To. The temperature, To, has a specific physical meaning with regard to the fracture mechanics properties of a material.

Section 4 describes the test specimens that can be used to develop valid Kjc data. The recommended specimen designs optimize the conditions of constraint, while at the same time they require the least amount of test material to produce a valid Kjc fracture toughness value. Care is taken to explain why certain other specimen types would be unsuitable for this type of work.