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SCC can be controlled by any of the following three approaches:

1 Design, which includes selection of the mechanical and materials aspects of components,

2 Controlling the materials, and

3 Controlling the environment.

Figure 5.11 Stress corrosion on a bar.

Figure 5.12 Stress corrosion cracking.

Source: Stress Corrosion Cracking/Industrial Metallurgists, LLC.

The source of the tensile stress which causes SCC may be externally applied stress or residual stresses. Externally applied stresses arise from applied mechanical loads such as tensile or bending loads. Residual stress is an internal stress that exists in a metal without an external load being applied. Residual stresses can result from cold working, heat treating, or welding. Increasing the yield strength of a metal is one way to improve its resistance to SCC because the threshold stress for SCC increases as the yield strength increases. The yield strength can be increased through alloying, heat treating, cold‐working, and combination of these approaches. There is one very important consideration when increasing the yield strength. The increase in strength must not be accompanied by a significant reduction of the metal’s toughness, because decreasing the toughness will have a detrimental effect on a metal’s resistance to SCC and on its fracture toughness.

The environmental factors, such as pH and temperature, also influence the severity of SCC. By controlling the environmental factors, SCC can be controlled.