1.1 This part of ISO 7539 covers procedures for designing, preparing, stressing, exposing and inspecting C-ring test specimens for investigating the susceptibility of a metal to stress corrosion. Analysis of the state and distribution of stress in the C-ring is presented. The term "metal" as used in this part of ISO 7539 includes alloys. 1.2 The C-ring is a versatile, economical specimen for determining the susceptibility to stress corrosion cracking of all types of metals in a wide variety of product forms including parts joined by welding. It is particularly suitable for tests of tube, rod and plate (see figure 1). Notched specimens may also be used (see 5.3.8). 1.3 C-ring specimens may be stressed to predetermined levels, using simple equipment for application of either constant load or constant strain.