Overview
ISO 20198:2026 specifies a standardized test method for determining the brittle crack arrest temperature (CAT) in metallic materials, specifically focusing on ferritic and bainitic steels. This international standard applies to rolled steel plates with a body-centred cubic (BCC) crystal lattice structure, which exhibit a ductile-to-brittle transition. The CAT test is relevant for steels with a maximum tensile strength of 950 MPa and thicknesses ranging from over 6 mm up to 200 mm, within a temperature range of −196 °C to +100 °C. The document also provides detailed requirements for isothermal crack arrest tests and the associated test procedures to ensure valid and reliable results.
Key Topics
Applications
The test method defined in ISO 20198:2026 is vital for industries where steel structures are exposed to low temperatures and high mechanical stresses, such as:
- Shipbuilding: Ensuring structural plates in vessels can arrest brittle cracks and prevent catastrophic failure, particularly in cold environments.
- Civil Engineering and Infrastructure: Assessing steel plates used in bridges, offshore platforms, and pressure vessels for their ability to resist brittle fracture propagation.
- Automotive and Transport: Relevant for heavy vehicles, railway carriages, and containers using high-strength rolled steels.
- Material Research and Quality Control: Enabling manufacturers to evaluate and certify new steel grades for critical applications, enhancing safety and longevity through robust material property assessment.
Related Standards
ISO 20198:2026 is complemented by several related documents for comprehensive testing of steel materials:
- ISO 20064:2019: Metallic materials - Steel - Method of test for the determination of brittle crack arrest toughness, Kca. Provides a related method for evaluating the lowest temperature at which crack propagation stops under a temperature gradient.
- ISO 7500-1: Metallic materials - Calibration and verification of static uniaxial testing machines - Ensures accurate force application during testing.
- ASTM E220-19: Standard Test Method for Calibration of Thermocouples by Comparison Techniques - Supports precise temperature measurements during fracture testing.
By following ISO 20198:2026, organizations ensure consistent, repeatable, and internationally recognized test results, supporting material selection, compliance, and safety for a broad range of engineering applications.
Keywords: ISO 20198:2026, brittle crack arrest temperature, CAT, rolled steel plates, ferritic steel, bainitic steel, isothermal crack arrest test, metallic materials, fracture testing, standard methods, temperature control, steel toughness, structural safety.