What is ISO 21153- Small crack growth rate of metals and alloys about?
ISO 21153 is an International Standard on the measurement of environmentally assisted small crack growth rate.
ISO 21153 specifies a method for determining the growth rate of small surface cracks in an aqueous environment (including atmospheric exposure) based on the measurement of the change in the size of the crack with exposure time. The methodology can be applied to stress corrosion and corrosion fatigue cracks propagation.
ISO 21153 describes the varied methodologies for the generation of crack precursors including accelerated generation of single pits.
Who is ISO 21153- Small crack growth rate of metals and alloys for?
ISO 21153 on measurement of environmentally assisted small crack growth rate is relevant to:
- Power generation, oil and gas, aerospace and automotive industry
- Mechanical engineers
- Quality testing authorities
Why should you use ISO 21153- Small crack growth rate of metals and alloys?
A core requirement for life prediction of structures and components for which environmentally assisted cracking is a potential failure mechanism is establishing a reliable methodology for quantifying the rate of damage development through the different stages of its evolution. For long cracks, standards for measuring environment assisted crack growth rates are well established, there are extensive data for key industrial sectors and there is a degree of confidence in their engineering application, the latter coupled with advanced monitoring and non-destructive inspection techniques. In service, cracks initiate predominantly at the surface (at corrosion pits, inclusions, physical defects) and the early development of those small cracks could represent a significant fraction of the life of a component.
However, there have been no standards for environmental-assisted small crack growth that guide the measurement process; simply recognition that the growth rate can be different from the crack growth for long cracks, that the rate will be sensitive to the local electrochemistry, near-surface gradients in microstructure, mechanical properties and residual stress, as well as loading conditions.
In this regard, ISO 21153 can help demonstrate the corrosion-resistant properties of metals, thus ensuring optimal performance and enhanced service-life of the end-application.
