GB/T 30064-2025 Active National standards

GB/T 30064-2025 Metallic materials—Method of constraint loss correction of CTOD fracture toughness for fracture assessment of steel components

Publish Date: 2025-12-02 Implement Date: 2026-07-01 For services related to genuine standard inquiry, procurement, translation, and other related services in China, please Contact Us

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Basic Information

Standard Code: GB/T 30064-2025

Standard Type: National standards

Standard Status: Active

is_force_gb: no

CCS Name: \n Test methods for the mechanical properties of metals

ICS Name: Mechanical testing of metal materials

Publish Date: 2025-12-02

Implement Date: 2026-07-01

Pages: 52 pages

Scope

In the fracture assessment of cracked steel structures, it is generally assumed that the fracture toughness specimens' resistance to fracture is equivalent to that of the structural components, but this assumption often leads to overly conservative fracture assessment results. This is due to the plastic constraint loss in the vicinity of the crack tip when the components are mainly subjected to tensile loads, while the fracture toughness specimens, due to bending loads, generate a highly constrained stress state in the vicinity of the crack tip. In recent years, high-strength steels with high yield strength-to-tensile strength ratios have been widely developed and applied. For these high-strength steels, the impact of constraint loss is very significant.
This document describes a method for converting the CTOD (crack tip opening displacement) fracture toughness obtained from fracture toughness specimen tests in the laboratory to the equivalent CTOD of structural components by considering the constraint loss. This method is also applicable to fracture assessments using stress intensity factors or J-integrals (see Chapter 9).
This document is applicable to the instability fracture caused by crack-like defects or fatigue cracks in ferritic structural steels. Instability fractures preceded by obvious ductile crack propagation are not applicable to this document.
The CTOD fracture toughness of structural steels is tested in accordance with the corresponding procedures specified in ISO 12135. The fracture assessment of cracked components is usually conducted using a method recognized by relevant institutions, such as FAD (Failure Assessment Diagram). This document does not provide a detailed description of the fracture assessment method.
This document is applicable to eliminating the frequent overly conservative nature of traditional fracture mechanics methods and accurately assessing the instability fracture initiation limit of structu