How does a creep test measure the slow deformation of a material under a constant load?

In materials testing, a creep test measures the slow, continuous deformation of a material subjected to a constant load over a prolonged period.12

During the test, a load is applied that is lower than the force required to cause instantaneous fracture. The resulting deformation, known as creep strain, is monitored over time using specialized instrumentation, typically an extensometer or a strain gauge.1

In addition to measuring strain, the test tracks the time it takes for the material to fail under the applied stress, a process often referred to as creep rupture or stress rupture. By plotting creep strain against time, engineers can use mathematical techniques to extrapolate data, allowing them to predict the long-term behavior of a material based on shorter-duration test results. This is particularly critical for designing components that operate under high stress and temperature, such as gas turbines.13