About:

Slow Strain Rate Test (SSRT) system is a versatile tool to study environmental assisted cracking behaviour under slow strain conditions, including stress corrosion cracking (SCC). In SSRT unit, a tensile test is performed on a conventional smooth tensile specimen, slowly elongated at a constant strain rate till specimen fracture. SSRT can be used for to study the creep behaviour of the materials, also. Through SSRT tool can be used on any material, many of the tests are applicable to metallic materials. SSRT is a method that helps to evaluate the corrosion behaviour of metals in a particular environment. It evaluates the effects of atmospheric conditions on stress corrosion cracking susceptibility of metals and alloys on material facture.

Facilities:

To study the susceptibility of metallic materials for environmentally assisted cracking, according to ASTM G-129. System offers 25 kN load cell with the associated hardwares. Loading mode is both constant and cyclic load. Under cyclic conditions, tests could be either load controlled, stress controlled or strain controlled. Under environment category, tests could be done room temperature, aqueous, and high temperature (700°C) conditions. All the tests are computer controlled. Samples could be round shape of 4 mm or 6 mm diameter following ASTM E8 or ASTM E8M; or flat specimens of 3 mm thick, 6 mm width and 25 mm gauge length; or CT specimen as per ASTM E647.

Specifications:

• Load: minimum 25 kN

• Loading modes: Constant and Cyclic

• Environment: Room temperature aqueous environment and high temperature environment

• Pull rod speed and Strain rate for 25 mm gauge length:

  a) Minimum pull rod speed: 2.6 x 10^-7 mm/s (strain rate= 1.0 x 10^-8 /s)

  b) Maximum pull rod speed: 3.8 x 10^-2 mm/s (strain rate= 1.5 x 10^-3 /s);

• Loading frequency: 0.02 Hz (minimum)

• Loading displacement: 25mm (minimum)

Cyclic Load Mode:

• When loading is in cyclic mode, it will be low frequency fatigue tests. Cyclic loading tests could be either load controlled, stress controlled or strain controlled. The loading pattern could be sinusoidal.

Constant Load Mode:

• Load cell response is to be used as a feedback signal for the computer to control the loading motor. This will help in equalising the measuring the load to the set load.