5.1 Data obtained by this test method shall not be used to predict the behavior of materials at elevated temperatures except in applications in which the conditions of time, temperature, method of loading, and stress are similar to those specified in the test.

5.2 This standard is particularly suited for quality control and development work. The data are not intended for use in design or predicting endurance at elevated temperatures.

1.1 This test method describes the determination of the temperature at which the specific modulus of a test specimen is realized by deflection in three-point bending. This temperature is identified as the distortion temperature. The distortion temperature is that temperature at which a test specimen of defined geometry deforms to a level of strain under applied stress of 0.455 MPa (66 psi) (Method A) and 1.82 MPa (264 psi) (Method B) equivalent to those used in Test Method D648. The test is applicable over the range of temperature from ambient to 300 °C.

Note 1: This test method is intended to provide results similar to those of Test Method D648 but are performed on a thermomechanical analyzer using a smaller test specimen. Equivalence of results to those obtained by Test Method D648 has been demonstrated on a limited number of materials. The results of this test method shall be considered to be independent and unrelated to those of Test Method D648 unless the user demonstrates equivalence.

1.2 There is no ISO standard equivalent to this test method.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.