1.1 This part of ISO 7539 covers procedures for designing, preparing and using U-bend 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 U-bend 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 wire or rod, or for machined specimens of circular cross-section. They can also be used for parts joined by welding. 1.3 The U-bend test is frequently used to establish whether a metal is susceptible to stress corrosion cracking in a given environment. It is used in laboratories to screen materials for susceptibility for specific applications and in service environments to assess the risk of failure. 1.4 The principal advantages of the test are its simplicity and its consequent adaptability for use in plant. A disadvantage is that stresses cannot be quantified with accuracy and if this is desired an alternative method of stressing should be used.