The International Organization for Standardization (ISO). This Part of BS EN ISO 7539 has been prepared under the direction of the Engineering Sector Board. It is identical with ISO 7539-3:1989. The European Standard EN ISO 7539-3:1995 has the status of a British Standard. 1995. 12p. 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