Brittleness Temprature ASTM D746 ISO 974

Brittleness temperature is an important property of plastics and elastomers that refers to the temperature at which 50% of the tested specimens exhibit brittle failure at specified impact conditions. This is a critical property that is used to evaluate the performance and durability of these materials under low-temperature conditions.

The test procedure for determining brittleness temperature involves securing specimens in a customer-specified specimen holder with a torque wrench at 5 in-lb. The specimen holder is then lowered into a bath at a specified temperature, and the specimens are impacted at 2000 ± 200 mm/s. The procedure is repeated at a lower temperature until enough data is generated to determine a brittleness temperature. Brittle failure is defined by ASTM D746 as fracture into 2 or more pieces, or any crack visible to the unaided eye. The specimens can be bent to an angle of 90° and examined for cracks at the bend.

The data collected from this test includes the test temperatures, number of failures, and the determined brittleness temperature. The brittleness temperature is the temperature at which 50% of the specimens fail.

Specimens used in this test come in three types: Type I, Type II, or Type III. ASTM specimens are Type I at 6.35 mm by 31.75 mm by 1.91 mm thick, while ISO specimens are Type III at 20 mm by 2.5 mm and 2.0 mm thick.

Brittleness temperature is a critical property for materials used in cold environments, such as automotive components or products that will be exposed to outdoor temperatures. Understanding the brittleness temperature of a material can help ensure its suitability for use in various applications and improve its overall performance and durability.