【国外标准】 Standard Test Method for Dynamic Tear Testing of Metallic Materials

5.1 The DT energy value is a measure of resistance to rapid progressive fracturing. In a number of applications, the enhanced resistance that may develop during about one plate thickness of crack extension from a sharp notch is of major interest. In the test method, a sufficiently long fracture path is provided so that the results serve as a measure of this property.5.2 Fracture surfaces of nonaustenitic steels tested in their temperature transition region have areas that appear bright and areas that appear dull. The bright, faceted appearing areas are termed “cleavage” fracture, and the dull appearing areas are termed “shear” fracture after their respective mode of fracture on a micro scale.5.3 This test method can serve the following purposes:5.3.1 In research and development, to evaluate the effects of metallurgical variables such as composition, processing, or heat treatment, or of fabricating operations such as forming and welding on the dynamic tear fracture resistance of new or existing materials.5.3.2 In service evaluation, to establish the suitability of a material for a specific application only where a correlation between DT energy and service performance has been established.35.3.3 For information, specifications of acceptance, and manufacturing quality control when a minimum DT energy is requested. Detailed discussion of the basis for determining such minimum values in a particular case is beyond the scope of this test method.1.1 This test method covers the dynamic tear (DT) test using specimens that are 3/16 in. to 5/8 in. (5 mm to 16 mm) inclusive in thickness.1.2 This test method is applicable to materials with a minimum thickness of 3/16 in. (5 mm).1.3 The pressed-knife procedure described for sharpening the notch tip generally limits this test method to materials with a hardness level less than 36 HRC.NOTE 1: The designation 36 HRC is a Rockwell hardness number of 36 on Rockwell C scale as defined in Test Methods E18.1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.5 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.1.6 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.