NDI Block 8 Study

What is a deterioration of a metal by chemical or electrochemical reaction with its environment or other materials?

• Stress Corrosion Cracking

• Uniform Etch

• Corrosion

• Corrosion Fatigue

If salt, or another ion source, is added to water, the conductivity is ___ and the rate of corrosion ___.

• increased; stablizes

• increased; increases

• decreased; increases

• increased; decreases

What can provide enough moisture for corrosion to occur?

• Water

• Snow from the Himalaya mountains

• Rain

• Condensation from damp air

What are the primary defenses against corrosion on an aircraft?

• Fatigue cracks and stress-corrosion cracks can be imaged using computed radiology

• Insulating dissimilar metals from each other and protecting metal surfaces from moisture

• Sheathing dissimilar metals from each other and surfaces from moisture

• Exposing dissimilar metals to each other and metal surfaces

What is the effect of the application of repeated or fluctuating stresses in a corrosive environment together?

• Stress Corrosion Cracking

• Uniform Etch

• Corrosion Embrittlement

• Corrosion Fatigue

Answer explanation

Note: Corrosion fatigue effects the rate of corrosion to increase if repeated and fluctuating stress continuously happens together

What is the severe loss of ductility of a metal?

• Stress Corrosion Cracking

• Uniform Etch

• Corrosion Embrittlement

• Corrosion Fatigue

Answer explanation

Note: Corrosion Embrittlement results from corrosive attacks, usually intergranular and often not visual

Definition of Ductility: (able to be deformed without losing toughness; pliable, not brittle)

Hint: "ducks likes brittle bread"

What is NOT a type of corrosion?

• Pitting

• Stress Corrosion Cracking

• Corrosion Fatigue

• Exfoliation

• Intergranular Attack

Which type of corrosion is characterized by a general overall reduction in thickness of a metal and readily detectable by visual means on exposed surfaces?

• Uniform Etch

• Pitting

• Exfoliation

• Intergranular Attack

• Stress Corrosion Cracking

Answer explanation

Note: Uniform Etch is the most common type of corrosion

Which type of corrosion is are small localized areas of corrosion and can vary from pinpoint size to relatively large areas?

• Uniform Etch

• Pitting

• Exfoliation

• Intergranular Attack

• Stress Corrosion Cracking

Answer explanation

Hint: Pitting looks like the crater of the moon

Which type of corrosion occurs particularly to aluminum alloys, preferentially along grain boundaries, and is NOT readily observable by visual means?

• Uniform Etch

• Exfoliation

• Pitting

• Intergranular Attack

• Stress Corrosion Cracking

Answer explanation

Hint: Intergranular Attack starts on grain boundaries and stays on grain boundaries

Definition of Preferentially: More favorably; *NDI= almost perfectly split