FST&R offers Creep and Stress Rupture Test methods to help manufacturing engineers better understand the long term stress has on metallic and non-metallic materials.

Expedited Creep and Stress Rupture Testing Services Are Available- Contact Us Today at 400-6411-668 or cs@fstestingdl.com

Creep and Stress Rupture Testing is designed to analyze the amount of stress a material can safely withstand until failure and elongation. These are important indications for products in the aerospace, automotive, power generation, medical, oil & gas and many other industries.

Creep and Stress Rupture Tests are conducted at temperatures up to +1300℃ to either ASTM E139 (creep and smooth-bar stress rupture) or ASTM E292 (notch tests).

Temperature and creep readings are recorded by computers and continuously monitored to ensure utmost accuracy. The creep test program is capable of recording strain readings up to 120 times per hour. This information is utilized to maintain temperature tolerances during a test and also to access a temperature history report for each completed test. The test temperatures are monitored by a centrally located multi-screen monitoring system.

Stress and creep rupture tests are also conducted in various environments under vacuum or inert atmospheric conditions. Tests are usually performed on materials that exhibit excessive corrosion at elevated temperatures in an air environment. The reduced section of a creep test specimen can also be strain-gaged as a means of measuring the amount of strain during testing.

The Creep and Stress Rupture Testing lab at FST&R has the capability to perform a variety of tests, such as: Creep Rupture, Stress Rupture, Cyclic Rupture, Static Notch and Embrittlement Relief.

Cyclic Rupture Testing is designed to load and unload a test sample at certain time intervals. The test temperatures range from room temperature to +1300℃. Prior to starting a test, four strain gages are attached to the test specimen to insure that bending strains are within specification requirements.

The Static Notch Test is performed at room temperature under a constant load for a minimum of 5 hours to determine if the material is notch sensitive at room temperature.

The Embrittlement Relief Test is also performed at room temperature, but for 200 hours under a load of some percentage of either the yield strength or ultimate tensile strength. Typically, this test is conducted in accordance with ASTM F 519 at 75% of the yield strength to determine if the material is susceptible to hydrogen embrittlement.

Additional tests available at FST&R:

•Tensile Bending Stress

•Biaxial Stress

•Flexural Properties

•Flexural Fatigue

•Strain and Material Deformation

•Flexural Stress

•Shear Rupture

•Shear Stress Strain

FST&R has thecapability of testing a number of various sizes and shapes of test specimens,some of which are shown below.

Manufacturing Technologies

On-Site Mechanical Engineering

The on-site Mechanical Engineering laboratory is staffed by specialists and engineers in product evaluation of actual prototype components and subassemblies. From custom design and fabrication of fixtures, to conducting the test, our mechanical engineers have the expertise and resources to assist our various testing departments in delivering data to customers in an efficient and timely manner.

Dedicated On-Site Creep and Stress Rupture Machine Shop

The on-site high-technology, full-service Machine Shop at FST&R encompasses a clean, temperature-controlled environment and state-of-the-art equipment, with the ability to machine all test specimens onsite. In addition to machining standard specimens, our Machine Shop has the ability and resource to custom-design and machine fixtures for testing finished parts, odd shapes, and difficult or exotic materials.

Our reputation for quality machining and superior turnaround times brings us production work from other laboratories and mills. With our advanced in-house capabilities, and substantial engineering experience, we are known as specialists in low-stress grinding and machining sub size specimens to very close tolerances.

FST&R provides the following standard tests:

ISO 204 & GB/T 2039（ISO 204 Modified）

Metallic materials — Uniaxial creep testing in tension — Method of test

These tests cover the determination of uninterrupted creep tests with continuous monitoring of extension, interrupted creep tests with periodic measurement of elongation, stress rupture tests where normally only the time to fracture is measured, and a test to verify that a predetermined time can be exceeded under a given force, with the elongation or extension not necessarily being reported. Based on ISO 204, GB/T 2039 slightly modifies in accordance with series of relevant Chinese standards.

ASTM E139

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

These tests cover the determination of the amount of deformation as a function of time (creep test) and the measurement of the time for fracture to occur when sufficient force is present (rupture test) for materials when under constant tensile forces at constant temperature.

ASTM E292

Standard Test Methods for Conducting Time-for-Rupture Notch Tension Tests of Materials

These tests cover the determination of the time for rupture of notched specimens under conditions of constant force and temperature.

Rupture life of notched specimens is an indication of the ability of a material to deform locally without cracking under multi-axial stress conditions, thereby redistributing stresses around a stress concentrator.

The notch test is used principally as a qualitative tool in comparing the suitability of materials for designs that will contain deliberate or accidental stress concentrators.

ASTM F519

Standard Test Method for Mechanical Hydrogen Embrittlement Evaluation of Plating/Coating Processes and Service Environments

This test method describes mechanical test methods and defines acceptance criteria for coating and plating processes that can cause hydrogen embrittlement in steels. Subsequent exposure to chemicals encountered in service environments, such as fluids, cleaning treatments or maintenance chemicals that come in contact with the plated/coated or bare surface of the steel, can also be evaluated.

Plating/coating Processes—Unstressed test specimens are cleaned, plated/coated, and baked (if applicable) in accordance with the specification to which the process is to be qualified. Specimens are then maintained under a sustained load in air to measure the time to rupture/completion of the test period.

Service Environments—Specimens are tested in the service environment. The sequence of exposure to the environment and loading shall be as defined in details of testing in service environments. If plated/coated test specimens are to be utilized for evaluating a service environment, then the plating/coating process must first be determined to be acceptable in accordance with plating/coating processes.

What is a Creep Test?

Creep is high temperature progressive deformation at constant stress. "High temperature" is a relative term dependent upon the materials involved. Creep rates are used in evaluating materials for boilers, gas turbines, jet engines, ovens, or any application that involves high temperatures under load. Understanding high temperature behavior of metals is useful in designing failure resistant systems.

A creep test involves a tensile specimen under a constant load maintained at a constant temperature. Measurements of strain are then recorded over a period of time.

Creep occurs in three stages: Primary, or Stage I; Secondary, or Stage II: and Tertiary, or Stage III. Stage I, or Primary creep occurs at the beginning of the tests, and creep is mostly transiently, not at a steady rate. Resistance to creep increases until Stage II is reached. In Stage II, or Secondary creep, The rate of creep becomes roughly steady. This stage is often referred to as steady state creep. In Stage III, or tertiary creep, the creep rate begins to accelerate as the cross sectional area of the specimen decreases due to necking or internal voiding decreases the effective area of the specimen. If stage III is allowed to proceed, fracture will occur.

The creep test is usually employed to determine the minimum creep rate in Stage II. Engineers need to account for this expected deformation when designing systems.

Like the Creep Test, Stress Rupture Testing involves a tensile specimen under a constant load at a constant temperature. Stress rupture testing is like creep testing aside from the stresses are being higher than those utilized within a creep testing. Stress rupture tests are utilized to find out the time it takes for failure so stress rupture testing is always continued until failure of the material occurs. Data is plotted similar to the graph above. A straight line or best fit bend is normally obtained at every temperature of interest. The Stress Rupture test is used to determine the time to failure and elongation.