Failures resulting from environmental cracking can be unanticipated and catastrophic because they occur in metals selected for their general corrosion resistance (like stainless steels).

• A. Environmental Cracking
• B. Uniform Corrosion
• C. Erosion
• D. Galvanic Corrosion

Answer: (A)

Environmental cracking is when a metal cracks and fails because the environment and applied stress work together, even if the metal resists general corrosion. Stainless steels are chosen for their broad corrosion resistance, but under certain conditions—such as in chloride-rich or strongly caustic environments, at elevated temperatures, or when there is sustained tensile stress—the material can experience cracking. This includes forms like stress corrosion cracking and corrosion fatigue, where a crack initiates and grows with little plastic deformation, potentially leading to sudden, catastrophic failure that isn’t obvious from surface condition.

Uniform corrosion, by contrast, is the even, gradual loss of material over a surface, not cracking. Erosion is wear from moving abrasive media, not chemical cracking. Galvanic corrosion arises from two different metals in electrical contact in an electrolyte, accelerating corrosion at the junction but not inherently causing cracking from environment-plus-stress.