NEBOSH Practice Test

Which of the following is a necessary condition for stress corrosion cracking to occur?

1. High humidity levels

2. A corrosive environment

3. Presence of moisture

4. High temperatures

The correct answer is: A corrosive environment

Stress corrosion cracking (SCC) specifically occurs when a material is subjected to tensile stress in the presence of a corrosive environment. This environmental factor is pivotal because it accelerates the degradation of the material, typically a metal, leading to the formation of cracks. The corrosive environment can include various elements such as chlorides, sulfides, or other aggressive chemicals that contribute to the material's deterioration. In the context of the other options, high humidity levels and the presence of moisture can contribute to corrosion but are not strictly necessary for SCC to occur. It is possible for SCC to occur in environments where humidity is not extremely high, as long as there is a sufficient concentration of corrosive agents. High temperatures can exacerbate the conditions for SCC but are not a fundamental requirement for its initiation.