Shocks and stresses increase corrosion by exposing the active layer of metal which was previously covered by the passive layer. How are these shocks and stresses described?

• A. Corrosion shocks and stresses
• B. Mechanical shock only
• C. Thermal shocks
• D. No effect

Answer: (A)

Shocks and stresses describe mechanical disturbances that break the protective passive film on a metal, exposing the underlying active metal to the environment. When the passive layer is damaged or ruptured, the metal’s surface becomes electrochemically active again, allowing corrosion processes to resume or accelerate at the exposed sites. This is why the phrase “corrosion shocks and stresses” is used—it links the mechanical events directly to a renewed or enhanced corrosion attack. The idea is that impact or applied stress disrupts passivity, creating anodic areas where dissolution proceeds, often leading to localized or rapid corrosion like pitting. In contrast, a term referring only to a mechanical event without the corrosion context, or one focused on temperature changes, wouldn’t capture this link between film breakdown and increased corrosion.