Which of the following is NOT a type of environmental cracking?

• A. Stress corrosion cracking
• B. Hydrogen-induced cracking and sulfide stress cracking
• C. Liquid metal embrittlement
• D. Cavitation erosion cracking

Answer: (D)

Environmental cracking happens when a corrosive environment and tensile stress work together to crack a material. Stress corrosion cracking fits this pattern, as a corrosive environment with stress drives cracks. Hydrogen-induced cracking and sulfide stress cracking involve hydrogen or sulfide-rich environments that embrittle the metal under stress. Liquid metal embrittlement occurs when a liquid metal penetrates or interacts with the solid metal under stress, causing brittle fracture. Cavitation erosion cracking, by contrast, is primarily mechanical damage from the collapse of vapor bubbles in a liquid, producing surface fatigue and cracks not driven by chemical attack under stress. So cavitation erosion cracking is not classified as environmental cracking.