ASTM E139 Creep, Creep Rupture and, Stress Rupture Test of Metallic Materials

Scope:

ASTM E139 test method is used to estimate the amount of deformation as a function of time in the creep test and the measurement of the time required to form a fracture when sufficient force is present for materials when under constant tensile forces at a constant temperature in the rupture test. It also includes the essential requirements for testing equipment. 

Test Procedure:

ASTM E139 test is an eight-step method, where initially all cross-sectional areas of the test specimen are measured. Then the original length is measured. The specimen needs to be washed carefully at reduced sections and the parts of the specimen which contact the grips in clean alcohol, acetone, or other suitable solvents that will not affect the metal being tested. Then a thermocouple is attached to the specimen to control the temperature during the test. Then the specimen is connected to the machine. Care must be taken while connecting the specimen to the machine. During the test, strain is to be measured for the creep or creep rupture test. Then force is applied to the specimen in such a manner that shock forces or excess forces due to inertia are avoided. The force may be applied in increments with strain readings taken between increments to provide stress-strain data for the application of the force. Then elongation and reduction in the area are measured. 

The information that should be in test report summaries is listed in these test methods. The goal is to make sure that interested parties receive all relevant and easily accessible information. Specifically, reports are given attention for the following reasons: 

• Results from various, accepted procedures differ significantly; which is why it is important to identify the method used.
• Later studies to establish key parameters are frequently impeded by the lack of specific information in published reports.
• The nature of prolonged tests frequently makes retests impractical, while at the same time making it difficult to remain within the recommended variations of some controlled variables.A thorough report enables the transmission of test results without assuming a level of control that wasn’t actually attained.

Video 01: Creep test

Specimen size:

The size and shape of test specimens shall be based primarily on the requirements necessary to obtain representative samples of the material being investigated or as required by the specification.

Data

Figure 01: Method of calculating elongation when the gauge length is marked on the reduced section of the specimen

Figure 02: Method of calculating elongation when the original gauge length includes fillets, shoulders, threads, etc.

Conclusion:

ASTM E139 test method is used to estimate the amount of deformation as a function of time in the creep test and the measurement of the time required to form a fracture when sufficient force is present for materials when under constant tensile forces at a constant temperature in the rupture test.