creeptests

Creep tests are materials experiments that measure time-dependent deformation under sustained load at elevated temperature. They are used to characterize a material's resistance to creep, determine its life under high-temperature service, and inform design and safety margins. Data from creep tests include creep rate, time to rupture, and deformation behavior across distinct creep stages.

Tests are conducted with specimens placed in furnaces or environmental chambers, loaded by constant stress or force, and heated to the target temperature. Deformation is tracked with extensometers, strain gauges, or digital image correlation. Tests may last from several hours to thousands of hours depending on material and conditions, and may be performed under air, vacuum, or controlled atmospheres to simulate service.

Key metrics include the minimum creep rate (steady-state rate), the total creep strain, and the time to rupture. Creep curves typically show primary, secondary (steady-state), and tertiary creep. Predictive models, such as Larson–Miller or Monkman–Grant correlations, are used to extrapolate long-term behavior.

Standards from organizations such as ASTM and ISO specify specimen geometry, temperature control, load levels, and data analysis methods to ensure comparability and repeatability. Creep testing informs material selection in high-temperature applications such as turbines, heat exchangers, and chemical processing equipment. Limitations include long test durations and the need for accelerated testing with caution in extrapolation.