ASTM G38-01 (R2021) pdf free download.Standard Practice for Making and Using C-Ring Stress-Corrosion Test Specimens.
1 .1 This practice covers the essential features of the design and machining, and procedures for stressing, exposing, and inspecting C-ring type of stress-corrosion test specimens. An analysis is given of the state and distribution of stress in the C-ring.
1.2 Specific considerations relating to the sampling process and to the selection of appropriate test environments are outside the scope of this practice.
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses after Si units are provided for information only and are not considered standard.
4. Significance and Use
4.1 The C-ring is a versatile, economical specimen for quantitatively determining the susceptibility to stress-corrosion cracking of all types of alloys in a wide variety of product forms. It is particularly suitable for making transverse tests of tubing and rod and for making short-transverse tests of various products as illustrated for plate in Fig. 1.
5. Sampling
5.1 Test specimens shall he taken from a location and with an orientation so that they adequately represent the material to he tested.
5.2 In testing thick sections that have a directional grain structure, it is essential that the C-ring be oriented in the section so that the direction of principal stress (parallel to the stressing bolt) is in the direction of minimum resistance to stress-corrosion cracking. For example. in the case of aluminum alloys (1), this is the short-transverse direction relative to the grain structure. If the ring is not so oriented it will tend to crack off-center at a location where the stress is unknown.
6. Specimen Design
6.1 Sizes for C-rings may be varied over a wide range, but C-rings with an outside diameter less than about 16 mm (/8 in.) are not recommended because of increased difficulties in machining and decreased precision in stressing. The dimensions of the ring can affect the stress state, and these considerations are discussed in Section 7. A typical shop drawing for the manufacture of a C-ring is shown in Fig. 2.
7. Stress Considerations
7.1 The stress of principal interest in the C-ring specimen is the circumferential stress. It should he recognized that this stress is not uniform (2, 3). First, there is a gradient through the thickness, varying from a maximum tension on one surface to a maximum compression on the opposite surface.ASTM G38 pdf download.