What is ISO 12135 about?
ISO 12135 discusses metallic materials. This international standard aims to help its users in identifying the most durable metals for their applications in construction, production of metallic products etc. ISO 12135 specifies methods for determining fracture toughness in terms of Κ, δ, J and R-curves for homogeneous metallic materials subjected to quasistatic loading.
ISO 12135 specimens are notched, pre-cracked by fatigue and tested under slowly increasing displacement. The fracture toughness is determined for individual specimens at or after the onset of ductile crack extension or at the onset of ductile crack instability or unstable crack extension.
Statistical variability of the results strongly depends on the fracture type. For applications that require high reliability, a statistical approach can be used to quantify the variability in fracture toughness in ductile to brittle transition region.
Note: ISO 12135 does not apply to:
- Fracture toughness at crack arrest is not covered
- Specify number of tests to be carried out or how the results of tests are applied or interpreted.
Who is ISO 12135 for?
ISO 12135 on unified test method for determination of quasistatic fracture toughness is applicable to:
- Metallic material suppliers to manufacturers
- Importers and dealers of metallic materials
- Manufacturers of metallic components and machinery
Why should you use ISO 12135?
Fracture toughness is the ability of material containing a crack of resist further fracture. Metallic materials have vast industrial applications, which is why they need to be robust and extensive mechanical testing is required.
ISO 12135 provides you with requirements for testing of metallic materials such as test specimens, pre-test requirements, apparatus and post-test crack measurements which helps you test extensively according to the unified standards. ISO 12135 gives you guidance on fracture toughness for stable and unstable crack extension, determination of resistance curves, initiation toughness, environments and stable crack extension which gives significant results on the strength and quality of the metallic components.
ISO 12135 guidelines ensure that you select the suitable metals that can withstand the stress they face in their operational life.
What’s changed since the last update?
BS ISO 12135:2021 supersedes BS 7448-1:1991 and BS 7448-4:1997, which are now withdrawn.
Changes in BS ISO 12135:2021 include -
- Formulae to calculate CTOD have been replaced with those based on rigid rotation assumption throughout; replacing the previous R-curve formulae based on CTOD from J. CTOD formulae for SENBs are now those based on recent research to include material yield to tensile strength ratio in the CTOD formulae
- Determination of J directly from displacement defined in terms of CMOD has been included, in addition to the methods based on load line displacement
- Where fatigue precrack straightness requirements cannot be met due to internal residual stresses, the application of modification techniques, originally developed for weld specimens is not permitted
- Rotation correction factor for compact specimens has been revised with a new formula
- Editorial changes have been made to improve consistency of terms and definitions used throughout the document