Types of Corrosion: An Overview for Mechanical Engineers

Question 1

What are the primary factors that contribute to stress corrosion cracking, and how do they interact to cause this type of corrosion?

Accepted Answer

Tensile stress, corrosive environment, susceptible material

Answer

Compressive stress, non-corrosive environment, resistant material

Answer

Shear stress, humid environment, inert material

Answer

Bending stress, acidic environment, brittle material

Question 2

Which type of corrosion occurs when a metal is exposed to both a corrosive environment and mechanical stress at the same time?

Accepted Answer

Stress corrosion cracking

Answer

Electrochemical corrosion

Answer

Corrosion fatigue

Answer

Fretting corrosion

Question 3

What type of corrosion involves the localized formation of small pits on the metal surface?

Accepted Answer

Pitting corrosion

Answer

Uniform corrosion

Answer

Galvanic corrosion

Answer

Intergranular corrosion

Question 4

What is the primary objective of stress relieving in reducing corrosion fatigue?

Accepted Answer

To reduce residual stresses

Answer

To increase surface hardness

Answer

To improve material toughness

Answer

To enhance corrosion resistance

Question 5

Which of the following is a characteristic of intergranular corrosion?

Accepted Answer

Occurs along grain boundaries

Answer

Forms pits on the metal surface

Answer

Results from mechanical stress

Answer

Is caused by galvanic coupling

Question 6

Which of the following is **NOT** a factor that can influence the rate of electrochemical corrosion?

Accepted Answer

Material's tensile strength

Answer

Oxygen concentration

Answer

pH level

Answer

Temperature

Question 7

What is the primary mechanism responsible for pitting corrosion?

Accepted Answer

Concentration of ions at specific sites on the metal surface

Answer

Depletion of oxygen at the metal surface

Answer

Formation of a passive film on the metal surface

Answer

Application of tensile stress to the metal

Question 8

Which of the following materials is most resistant to uniform corrosion?

Accepted Answer

Stainless steel

Answer

Pure iron

Answer

Copper

Answer

Aluminum

Question 9

What is the primary purpose of anodic polarization in corrosion control?

Accepted Answer

To protect the metal from corrosion

Answer

To increase the rate of corrosion

Answer

To remove corrosion products from the metal surface

Answer

To measure the corrosion potential of the metal

Question 10

What is the mechanism of intergranular corrosion?

Accepted Answer

Preferential attack of grain boundaries

Answer

Formation of a protective oxide layer on the metal surface

Answer

Selective dissolution of a specific phase in the metal

Answer

Corrosion along slip planes in the metal

Question 11

Which statement best reflects the ethical and environmental considerations of sustainable corrosion management?

Accepted Answer

Sustainable corrosion management prioritizes a balance between technical, economic, and environmental factors to minimize overall impact.

Answer

Corrosion prevention should focus primarily on cost-effectiveness, even if it harms the environment.

Answer

Using hazardous materials for corrosion prevention is acceptable if it enhances product performance.

Question 12

Which type of corrosion arises from electrochemical reactions between a metal and its surrounding environment?

Accepted Answer

Electrochemical corrosion

Answer

Stress corrosion cracking

Answer

Corrosion fatigue

Answer

Hydrogen embrittlement

Question 13

Which type of corrosion results from repeated mechanical loading and unloading in a corrosive environment?

Accepted Answer

Corrosion fatigue

Answer

Stress corrosion cracking

Answer

Electrochemical corrosion

Answer

Fretting corrosion

Question 14

What is the primary protective mechanism against corrosion in stainless steels?

Accepted Answer

Formation of a passive chromium oxide layer

Answer

Application of corrosion-resistant coatings

Answer

Formation of a sacrificial zinc layer

Answer

Cathodic protection using an external power source

Question 15

How does uniform corrosion differ from localized corrosion?

Accepted Answer

Uniform corrosion affects the entire exposed surface, while localized corrosion affects specific areas of the surface.

Answer

Uniform corrosion is more prevalent in stainless steels.

Answer

Localized corrosion is less severe than uniform corrosion.

Question 16

Which of the following environmental factors can significantly accelerate corrosion processes?

Accepted Answer

High temperature and humidity

Answer

Absence of oxygen

Answer

Neutral pH

Answer

Low temperature and dry conditions

Question 17

What is the primary function of corrosion inhibitors?

Accepted Answer

To form a protective layer on the metal surface, reducing its reactivity

Answer

To reduce the oxygen content in the corrosive environment

Answer

To increase the pH of the corrosive environment

Answer

To increase the electrical resistance of the metal

Question 18

Which type of corrosion occurs when two dissimilar metals are in electrical contact in the presence of an electrolyte?

Accepted Answer

Galvanic corrosion

Answer

Pitting corrosion

Answer

Uniform corrosion

Answer

Intergranular corrosion

Question 19

How do cracks and crevices influence corrosion behavior?

Accepted Answer

They can act as sites for localized corrosion initiation and accelerate its propagation.

Answer

They have no significant effect on corrosion

Answer

They reduce the overall corrosion rate by providing a sheltered area

Question 20

Which type of corrosion arises when a metal is in contact with an electrolyte and subjected to an electrical current?

Accepted Answer

Electrochemical corrosion

Answer

Erosion corrosion

Answer

Stress corrosion cracking

Answer

Atmospheric corrosion

Question 21

Stress corrosion cracking occurs when a metal is subjected to:

Accepted Answer

Tensile stress and a corrosive environment

Answer

Compressive stress and an acidic environment

Answer

Elevated temperature and a humid environment

Answer

Alternating stress and a neutral environment

Question 22

Which type of corrosion is characterized by progressive deterioration caused by repeated mechanical stresses?

Accepted Answer

Corrosion fatigue

Answer

Fretting corrosion

Answer

Microbiologically influenced corrosion

Answer

Cavitation erosion

Question 23

In electrochemical corrosion, what is the role of anodic and cathodic reactions?

Accepted Answer

Anodic reactions dissolve metal into ions, while cathodic reactions consume electrons and produce hydroxide ions.

Answer

Anodic reactions produce metal ions, while cathodic reactions release hydrogen gas.

Answer

Anodic reactions consume oxygen, while cathodic reactions produce metal ions.

Question 24

A common method to prevent stress corrosion cracking is:

Accepted Answer

Stress-relieving heat treatments

Answer

Applying protective coatings

Answer

Using sacrificial anodes

Answer

Increasing the oxygen content in the environment

Question 25

Pitting corrosion is recognized by its:

Accepted Answer

Localized, hole-like defects on metal surfaces

Answer

Intergranular cracking along grain boundaries

Answer

Extensive surface discoloration

Answer

Uniform thinning of metal components

Question 26

Which material exhibits remarkable resistance to general corrosion?

Accepted Answer

Stainless steel

Answer

Aluminum

Answer

Carbon steel

Answer

Copper

Question 27

The primary cause of galvanic corrosion is:

Accepted Answer

Direct contact between dissimilar metals in the presence of an electrolyte

Answer

Presence of oxygen and moisture

Answer

Exposure to high temperatures

Answer

Mechanical stress on the metal surface

Question 28

Crevice corrosion is commonly found in environments like:

Accepted Answer

Marine environments and areas with stagnant water

Answer

Industrial settings with high levels of pollution

Answer

Extremely dry environments

Answer

High-vacuum systems

Question 29

What is the primary function of a cathodic protection system?

Accepted Answer

To protect metal structures from corrosion by making them the cathode in an electrochemical reaction

Answer

To remove oxygen from the environment surrounding the metal

Answer

To increase the flow of electrons to the metal surface