1.1 This part of ISO 7539 covers procedures for designing, preparing and using bent-beam test specimens for investigating the susceptibility of a metal to stress corrosion. The term "metal" as used in this part of ISO 7539 includes alloys. 1.2 Bent-beam specimens may be used to test a variety of product forms. They are used principally for sheet, plate or flat extruded material, which conveniently provides flat specimens of rectangular cross-section, but may also be employed for cast material, wire or rod, or for machined specimens of circular cross-section. They can also be used for parts joined by welding. 1.3 Since the preparation of the specimens and the apparatus used for stressing them are both simple and inexpensive, bent-beam specimens are especially suitable for multiple testing and for atmospheric stress corrosion tests. 1.4 Bent-beam specimens are usually tested under nominally constant strain conditions but nominally constant load conditions may be employed. In either case local change of curvature in the specimen when cracking occurs results in changing conditions during crack propagation. The "test stress" is taken as the highest surface tensile stress existing at the start of the test.