ASTM E139 Test Methods for Conducting Creep, Creep-Rupture, and Stress-Rupture Tests of Metallic Materials

Get Certified ASTM E139 Creep and Rupture Testing

ASTM E139 testing helps suppliers, material manufacturers, engineers, and quality-control personnel determine the performance of metallic materials under sustained stresses and temperatures. Technicians prepare and examine the specimens, set the required load and temperature conditions, and observe them during the test. The recorded deformation, stress, temperature, and time data are reviewed by the analysts, and the appropriate creep or rupture values are determined. The results can help in material selection, long-term performance evaluation, product development, and quality control activities.

• Material Type: Metallic materials and applicable alloys evaluated for creep or rupture behavior. 
• Property Measured: Creep deformation, creep rate, rupture time, and other appropriate creep or rupture properties. 
• The method: Testing consists of applying a sustained load or stress to a metallic specimen, keeping the temperature constant, and then observing the specimen over time. 
• Result: Results include strain, deformation, creep rate, stress, temperature, and time to rupture (as applicable). 
• Test Limitations: Results depend on the test conditions/circumstances described and on the material, specimen dimensions, applied stress, test duration, and temperature. 
• Environmental Conditions: Temperature and applicable test-environment conditions are controlled, as they can affect the creep and rupture behavior.
• Applications: High-temperature material evaluation, engineering design, material selection, alloy development, quality control, and long-term evaluation. 

What are the uses of ASTM E139 testing?

ASTM E139 testing provides engineers and technical staff with an indicator of the response of metallic materials to sustained stress for a prolonged period of time. The test indicates information on time-dependent deformation, creep rates, and rupture characteristics under given conditions of temperature and loading. These results are used by technicians and analysts to gain insight into long-term material performance and for engineering decision-making. The data can also be useful for comparing materials and assessing their performance for critical service conditions. The test helps to:

• Creep Evaluation: Measures the deformation of a metal material as a function of time when subjected to a constant stress. 
• Rupture Assessment: Determines the properties and times-to-failure of rupture under given conditions. 
• Material Comparison: A comparison of the creep and rupture behavior of the appropriate metallic material/ alloys. 
• Material Selection: Helps in choosing materials for sustained-load and elevated-temperature applications.
• Engineering Design: Supplies mechanical-performance information for appropriate engineering uses. 
• Quality Control: Assists with checking the uniformity of materials and their effectiveness. 
• Materials Development: Helps develop and test metallic materials and alloys.

Which Materials Can Be Tested According to ASTM E139?

ASTM E139 applies to metallic materials for which the creep, creep-rupture, or stress-rupture properties are needed. The method is especially valuable when engineers want to comprehend the behavior of metals subjected to sustained loading for extended periods of time at controlled temperatures. Techs can make representative specimens from production materials, metallic alloys, and materials in development. The specimens selected must satisfy the required dimensions, condition, and test configuration for the selected type of test. The method applies to:

• Material Type: Metallic materials evaluated for time-dependent deformation and rupture behavior. 
• Metallic Alloys: Supports creep and rupture evaluation of applicable alloy grades. 
• High-Temperature Materials: Allows evaluation of metals intended for elevated-temperature service. 
• Production Materials: Supports testing of representative specimens from manufacturing or production batches. 
• Development Materials: Helps engineers evaluate new or modified metallic materials for long-term performance.

Why Is ASTM E139 Testing Important?

This process of progressive deformation over time is referred to as creep and can occur in metallic materials under sustained stress, especially at high temperatures. Repeated exposure may lead to bursting. ASTM E139 is a standard method for assessing these behaviors in a controlled setting. The results are useful for the analysis of high-temperature and sustained-stress material performance, comparative analysis of metallic materials, material selection, and evaluation of all the alloys for their application to sustained stress at high temperature.

ASTM E139 Testing Process and Data Collection

Technicians identify the metallic material and prepare a representative specimen. They measure and inspect the specimen before mounting it in the testing equipment. The technician establishes the required temperature and applies the specified sustained load or stress. Technicians monitor and record deformation, strain, test duration, and rupture information as applicable. Analysts review the collected data and determine the relevant creep or rupture characteristics.

Common Challenges and Troubleshooting

Specimen misalignment, inappropriate loading, temperature changes, wrong specimen sizes, errors in measuring deformation, and unstable equipment can change the results of ASTM E139. Technicians must check the specimens carefully, make sure the equipment is properly calibrated, keep the temperature the same, and place the specimens in the correct position. Technicians and analysts should check specimen preparation, the size of the specimen, the stress that was applied, temperature stability, the measurements of deformation, test time, and equipment used when the results are not as expected.

• The laboratory reports creep strain as a percentage (%) and creep rate in %/h or s⁻¹, as applicable.
• The analyst reports the sustained applied stress in MPa and the test temperature in °C.
• The laboratory records the rupture time in h or s and documents the specimen’s rupture behavior and failure characteristics.
• The technician records the measured deformation in mm, where applicable, to quantify dimensional changes during testing.
• The analyst compares the measured creep and rupture results with material specifications, design requirements, or reference data to evaluate long-term performance.

Link to ASTM E139