Testing PROCESSES
Slow Strain Tensile Test
A Slow Strain Tensile (SST) Test, sometimes called a Constant Extension Rate Test (CERT), is a specialized variation of tensile testing that applies strain at a very slow, controlled rate. This method is designed to evaluate a material’s susceptibility to stress corrosion cracking (SCC) or other time-dependent failure mechanisms that occur under simultaneous mechanical stress and corrosive environments. For critical fasteners, the SST Test provides essential insight into long-term reliability in demanding applications.
How the Test is Performed
Specimen Preparation – A fastener or machined sample is prepared and placed in a tensile testing machine.
Controlled Strain Application – Instead of applying a load rapidly, strain is applied at a very slow and constant rate.
Environmental Conditioning – The specimen may be exposed to a corrosive medium (such as a salt solution, hydrogen sulfide, or other environment relevant to service conditions).
Monitoring and Measurement – Load, elongation, and time to failure are carefully recorded.
Result Analysis – The data is analyzed to determine susceptibility to stress corrosion cracking or other strain-related failures.
Why It is Performed
The SST Test is performed to ensure that fasteners can maintain their integrity when subjected to simultaneous mechanical stress and corrosive environments. Standard tensile tests may not reveal susceptibility to stress corrosion cracking, which can lead to sudden, catastrophic failures.
Detects vulnerability to stress corrosion cracking (SCC)
Evaluates long-term durability under slow, sustained loading
Confirms material and heat treatment effectiveness in corrosive environments
Ensures safe, reliable performance of fasteners in mission-critical applications
Application to Engineered Fasteners
Engineered fasteners are often used in aerospace, oil & gas, marine, nuclear, and defense applications where they face both sustained loads and harsh environments. Slow Strain Tensile Testing helps TSP Manufacturing ensure that these fasteners:
Resist cracking and embrittlement under real-world service conditions
Maintain strength and ductility in corrosive environments
Provide assurance of long-term performance where standard tensile testing is not sufficient
Prevent catastrophic failures that could compromise equipment safety and reliability
Standards & Compliance
At WN Global, Slow Strain Tensile Testing is conducted in compliance with ASTM, NACE, ISO, and customer-specific standards. All testing equipment is calibrated, and procedures are performed by qualified personnel to ensure accuracy, repeatability, and traceability. This commitment to recognized testing standards ensures that our engineered fasteners and machined components meet the strict reliability requirements demanded by the industries we serve.
Testing Processes
DOING WHATEVER IT TAKES
Putting Manufacturing Exellence Into Practice
The manufacturing processes, testing capabilities, and quality systems featured throughout WN Global support the production of critical components and engineered fastening solutions across demanding industries. Connect with our team to learn how our manufacturing capabilities can support your project requirements.
