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Creep & Stress Rupture Testing
Creep and rupture tests are utilized to evaluate and predict the time-dependent behavior of metals and composites at elevated temperatures under applied stress in tensile or compressive modes. Deformation is measured as a function of time. Understanding material properties is essential for designing nuclear safety-related components and systems used during processing, transport and storage.
This data may be used to develop advanced materials fit for purpose, develop operating limits for existing materials in new environments, predict how joining techniques will perform under real-life conditions (i.e. welds), estimate service life, develop maintenance schedules and reduce the risk of catastrophic failures of turbine blades, steam pipes and other equipment under high-temperature and stress conditions.
Lucideon has 22 creep / stress rupture test stands available, that are able to test specimens up to 10-1/8" in length ranging from carbon steel alloys and stainless steels, to Inconel alloys. Tests may be conducted up to 1650°F in temperature and 10,000 lbs in load. Temperature and creep readings are recorded and monitored continuously to ensure accuracy of results.
Creep testing (creep-rupture, stress-rupture, stress-relaxation) is conducted to determine the deformation (creep) of a material when subjected to a prolonged load at a constant temperature.
- A creep test has the objective of measuring creep and creep rates occurring at stresses usually well below those which would result in fracture.
- In a creep-rupture test, progressive specimen deformation and the time to rupture are measured. In general, deformation during this test is much larger than that developed during a creep test.
- A stress-rupture test is a test in which time to rupture is measured.
- The stress-relaxation test is similar to the creep test, except the load continually decreases instead of remaining constant. The load is reduced at intervals to maintain a constant strain. This is often used to determine torqueing schedules for bolted assemblies.
ASTM Test Methods
- ASTM D2990 Compressive Creep and Creep-Rupture of Plastics
- ASTM E139 Creep, Creep-Rupture & Stress Rupture Tests of Metallic Materials
- ASTM E292 Conducting Time-for-Rupture Notch Tension Tests of Materials
- ASTM E328 Stress Relaxation for Materials and Structures.