Magnetic Particle Inspection Level 1 Practice Exam

What factor can lead to stress corrosion cracking?

1. Excessive heating

2. Combined tensile stress and environment

3. Rapid cooling

4. Overloading

The correct answer is: Combined tensile stress and environment

Stress corrosion cracking is a complex phenomenon that occurs when a susceptible material is subjected to both tensile stress and a corrosive environment. The combination of these two factors significantly increases the likelihood of cracking developing over time. Tensile stress can arise from various sources, including mechanical loading or residual stresses from fabrication processes. When these stresses are present along with a corrosive medium—such as chlorides in the case of stainless steel—the material can become more vulnerable to cracking. The corrosive environment promotes the propagation of microcracks, which can grow and lead to catastrophic failure if not properly managed. While excessive heating, rapid cooling, and overloading can also induce stress and affect material properties, they do not specifically address the unique interaction between tensile stress and a corrosive environment that is characteristic of stress corrosion cracking. Therefore, the factor that directly contributes to stress corrosion cracking is indeed the combination of tensile stress and the corrosive environment.