NACE - National Association of Corrosion Engineers Corrosion Theory and Forms Questions and Answers

Question 1

For a corrosion cell to exist, which four elements must be present?

Accepted Answer

Anode, cathode, metallic pathway, and electrolyte

Answer

Anode, conductor, acidic solution, and current

Answer

Two dissimilar metals, water, and a protective coating

Answer

Cathode, noble metal, ionic path, and voltage source

Question 2

A steel pipeline is connected with brass fittings. In the presence of an electrolyte, which phenomenon is most likely to occur and why?

Accepted Answer

The steel pipeline will corrode because it is more anodic than brass.

Answer

The brass fittings will corrode because they are smaller in surface area.

Answer

Both the steel and brass will corrode at an equal rate.

Answer

The steel will be cathodically protected by the brass fittings.

Question 3

Which form of corrosion is characterized by a localized attack that creates small holes or cavities in the metal, often initiated by a localized breakdown of a passive film?

Accepted Answer

Pitting corrosion

Answer

Uniform corrosion

Answer

Intergranular corrosion

Answer

Erosion corrosion

Question 4

A technician inspects a stainless steel component that was welded and notices severe corrosion along the heat-affected zone next to the weld. This is most characteristic of which form of corrosion?

Accepted Answer

Intergranular corrosion

Answer

Galvanic corrosion

Answer

Crevice corrosion

Answer

Stress corrosion cracking

Question 5

Crevice corrosion is a form of localized corrosion that occurs in stagnant microenvironments. Which condition is a primary driver for the initiation of crevice corrosion?

Accepted Answer

A differential in oxygen concentration between the crevice and the bulk environment

Answer

High fluid velocity across the surface

Answer

The presence of two dissimilar metals in direct contact

Answer

Uniform tensile stress across the entire component

Question 6

Which of the following describes environmentally assisted cracking (EAC)?

Accepted Answer

Brittle fracture of a normally ductile material resulting from the combined action of a corrosive environment and tensile stress.

Answer

A purely mechanical failure due to cyclic loading.

Answer

Uniform loss of material due to a chemical reaction with the environment.

Answer

Accelerated corrosion caused by the impingement of a high-velocity fluid.