stress corrosion
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What are the main factors of stress corrosion, and which media can cause stress corrosion in carbon steel and low-alloy steel?
Stress corrosion is the result of the combined action of a corrosive medium and tensile stress; therefore, aside from the medium, the most important factor is stress. The sources of stress can be external: working stress during the operation of the component, thermal stress, etc. It can also be the residual stresses resulting from component manufacturing: residual stresses from welding, cold working, and installation.
Stress corrosion occurs only under the combined effect of tensile stress and a corrosive environment. For carbon steel and low-alloy steel, stress corrosion can easily occur in environments such as NaOH, wet hydrogen sulfide, high-temperature and high-pressure hydrogen environments, and liquid ammonia.
It’s not just tensile stress, right! There must be stress in the compression direction as well! For example: at a corner, the outer side is under tensile stress while the inner side is under compressive stress!
Brittle fracture of metal materials or metal structures caused by the combined effect of tensile stress and a specific corrosive environment. It must be tensile stress. Carbon steel and low-alloy steel are susceptible to stress corrosion in environments such as alkaline solutions, nitrate solutions, wet hydrogen sulfide environments, and anhydrous liquid ammonia. Austenitic stainless steels are prone to stress corrosion in the presence of chloride ions, chlorides combined with steam, wet hydrogen sulfide, and alkaline solutions. Molybdenum-containing austenitic stainless steels are vulnerable to stress corrosion in alkaline solutions, chloride aqueous solutions, sulfuric acid plus copper sulfate aqueous solutions, etc