Slow Strain Rate Testing

Displacement Control

Motorized drive systems maintain a pull speed that is thousands of times slower than a standard tensile test. When performing slow strain rate testing, the machine must provide a smooth motion to avoid artificial load spikes that could trigger premature cracking.

Ductility Ratio

Performance of the material is evaluated by comparing the elongation and reduction in area in the test environment to those in an inert control. A low ratio indicates that the environment has caused the metal to become brittle and prone to cracking. This comparison is the primary output used to qualify an alloy for safety-critical service.

Surface Integrity

Examination of the fractured specimen under a microscope reveals whether the failure was transgranular or intergranular. Because slow strain rate testing mimics the slow loading found in real equipment, it is a reliable predictor of long-term field performance. This method identifies hidden vulnerabilities in the grain structure that a faster test would miss.