ISO 27306:2016
Metallic materials - Method of constraint loss correction of CTOD fracture toughness for fracture assessment of steel components

Standard No.

ISO 27306:2016

Release Date

2016

Published By

International Organization for Standardization (ISO)

Latest

ISO 27306:2016

Scope

In fracture assessments of steel structures containing cracks, it has generally been assumed that the fracture resistance of fracture toughness specimens is equal to the fracture resistance of structural components. However, such an assumption often leads to excessively conservative fracture assessments. This is due to a loss of plastic constraint in structural components, which are subjected mainly to tensile loading. By contrast, fracture toughness specimens hold a constrained stress state near the crack-tip due to bending mode. The loss of constraint is significant for high strength steels with high yield-to-tensile ratios (= yield stress/tensile strength) which have been extensively developed and widely applied to structures in recent years. This International Standard specifies a method for converting the CTOD (crack-tip opening displacement) fracture toughness obtained from laboratory specimens to an equivalent CTOD for structural components, taking constraint loss into account. This method can also apply to fracture assessment using the stress intensity factor or the J-integral concept (see Clause 9). This International Standard deals with the unstable fracture that occurs from a crack-like defect or fatigue crack in ferritic structural steels. Unstable fracture accompanied by a significant amount of ductile crack extension and ductile fractures are not included in the scope hereof. The CTOD fracture toughness of structural steels is measured in accordance with the established test methods, ISO 121351) or BS 7448-1. The fracture assessment of a cracked component is done using an established method such as FAD (Failure Assessment Diagram) in the organization concerned, and reference is not made to the details thereof in this International Standard. This International Standard can be used for eliminating the excessive conservatism frequently associated with the conventional fracture mechanics methods and accurately assessing the unstable fracture initiation limit of structural components from the fracture toughness of the structural steel. This is also used for rationally determining the fracture toughness of materials to meet the design requirements of performance of structural components.

ISO 27306:2016 Referenced Document

• ASTM E1921-15 Standard Test Method for Determination of Reference Temperature, To, for Ferritic Steels in the Transition Range
• ISO 12135:2002 Metallic materials - Unified method of test for the determination of quasistatic fracture toughness
• ISO 6892-1:2016 Metallic materials - Tensile testing - Part 1: Method of test at room temperature
• ISO 6892-3:2015 Metallic materials - Tensile testing - Part 3: Method of test at low temperature
• JIS G 3106:2008 Rolled steels for welded structure

ISO 27306:2016 history

• 2016 ISO 27306:2016 Metallic materials - Method of constraint loss correction of CTOD fracture toughness for fracture assessment of steel components
• 2009 ISO 27306:2009 Metallic materials - Method of constraint loss correction of CTOD fracture toughness for fracture assessment of steel components