1.1 These test methods cover bend testing for ductility of materials. Included in the procedures are four conditions of constraint on the bent portion of the specimen:

• 1.1.1 In the guided-bend test the specimen is bent by a mandrel of defined dimensions midway between two supports separated by a defined space.

• 1.1.2 In the semi-guided bend test, the specimen is bent, while in contact with a mandrel, through a specified angle of bend or to a specified inside radius of bend (r) that is measured while under the bending force.

• 1.1.3 In the free-bend test, the ends of the specimen are brought toward each other, but no transverse force is applied to the bend itself and there is no contact of the concave inside surface of the bend with other material.

• 1.1.4 In the bend-and-flatten test, a transverse force is applied to the bend such that the legs make contact with each other over the length of the specimen.

1.2 After bending, the convex surface of the bend is examined, and cracks, or surface irregularities, or both, are evaluated. If the specimen fractures, the material has failed the test. When complete fracture does not occur, the criterion for failure is as specified by the material or product specification, or code that cites Test Methods E290, or customer requirements.

Any cracks within one thickness of the edge of the specimen are not considered a bend test failure. Cracks occurring in the corners of the bent portion shall not be considered significant unless they exceed the size specified for corner cracks in the material or product specification, or code that cites Test Methods E290, or customer requirements.

1.3 The values stated in SI units are to be regarded as standard. Inch-pound values given in parentheses were used in establishing test parameters and are for information only.

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.

5.1 Bend tests for ductility provide a simple way to evaluate the quality of materials by their ability to resist cracking or other surface irregularities during one continuous bend. No reversal of the bend force shall be employed when conducting these tests.

5.2 The type of bend test used determines the location of the forces and constraints on the bent portion of the specimen, ranging from no direct contact to continuous contact.

5.3 The test may terminate at a given angle of bend over a specified radius of bend or continue until the specimen legs are in contact. The angle of bend may be measured while the specimen is under the bending force (usually when the guided-bend or semi-guided bend test is employed), or after removal of the force as when performing a free-bend test. Product requirements for the material being tested determine the method used.

5.4 Materials with an as-fabricated cross section of rectangular, round, hexagonal, or similar defined shape may be tested in full section to evaluate their bend properties by using the procedures outlined in these test methods, in which case relative width and thickness requirements do not apply.