ASTM E290, ISO 7438, and JIS Z2248 describe the requirements for bend testing for ductility of metallic materials. The bend test /flexure test helps provide a visual indication of the ductility of the material. The guided bend test method requires the specimen to be loaded at its center point with a mandrel or plunger while being supported at the ends. The specimen is bent to a predetermined angle or until the specimen fractures. The convex side of the specimen is visually inspected for cracks or defects, and failure is determined by the size of the cracks and imperfections allowed by the material specification.

ASTM E290 covers bend testing for ductility of materials. Included in the procedures are four conditions of constraint on the bent portion of the specimen; a guided-bend test using a mandrel or plunger of defined dimensions to force the mid-length of the specimen between two supports separated by a defined space; a semi-guided-bend test in which the specimen is bent, while in contact with a mandrel, through a specified angle or to a specified inside radius (r) of curvature, measured while under the bending force; a free-bend test in which the ends of the specimen are brought toward each other, but in which 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; a bend and flatten test, in which a transverse force is applied to the bend such that the legs make contact with each other over the length of the specimen.

ASTM E290 Standard Test Methods for Bend Testing of Material for Ductility
ISO 7438 Metallic materials -- Bend test