Corrosion Engineering Multiple Choice Questions on “Prevention – Material Selection and Design – 1”.
1. The most common method of preventing corrosion is the selection of the proper metal or alloy for a particular corrosive service.
a) True
b) False
Answer: a
Clarification: There is no such single material that can be used in all environment conditions and all temperature ranges. So, it is important to select a proper metal or alloy for a particular corrosive service. It prevents or reduces the corrosion damage of the metallic structure.
2. Which of the following composition range is correct regarding stainless steel?
a) 11.5 to 30% chromium and 10 to 22% nickel
b) 11.5 to 30% chromium and 0 to 22% nickel
c) 0 to 30% chromium and 0 to 22% nickel
d) 0 to 30% chromium and 10 to 22% nickel
Answer: b
Clarification: Stainless steel is the generic name for a series of more than 30 different alloys with composition ranges from 11.5% to 30% chromium and 0 to 22% nickel and other alloying elements.
3. Which of the following types of corrosion in which stainless steels are more susceptible than ordinary steels?
a) Pitting corrosion
b) Stress-corrosion cracking
c) Intergranular corrosion
d) Stress-corrosion cracking, pitting and intergranular corrosion
Answer: d
Clarification: Stainless steels are more susceptible to localized corrosion such as intergranular corrosion, stress-cracking corrosion, and pitting corrosion than ordinary steels. Instability of oxide layer in severe corrosive conditions and sensitizing temperature are the reasons for the susceptibility of stainless steel.
4. Which of the following metal is the best material selection combination for the nitric acid environment?
a) Tin
b) Nickel and its alloys
c) Stainless steels
d) Steel
Answer: c
Clarification: Stainless steels are the best combination of metal for the nitric acid environment. Stainless steels readily form a passive oxide film in nitric acid. This minimizes or reduces the corrosion damage.
5. Which of the following metal is the best material selection combination for the caustic environment?
a) Titanium
b) Nickel and its alloys
c) Steels
d) Aluminum and its alloys
Answer: b
Clarification: Nickel and its alloys are the best combination of metal for the caustic environment. Metals such as titanium and high tensile strength steels are prone to caustic embrittlement.
6. Which of the following metal is the best material selection combination for distilled water?
a) Tin
b) Lead
c) Titanium
d) Nickel
Answer: a
Clarification: Tin is the best combination of metal for distilled water. Tin or tin coatings are almost always chosen as a container or piping material for very pure distilled water.
7. Which of the following metal is/are the correct combination for reducing or non-oxidizing environment?
a) Nickel and its alloys
b) Copper and its alloys
c) Stainless steels
d) Nickel, copper and its alloys
Answer: d
Clarification: Nickel, copper and its alloys are the correct combinations of metals for reducing or non-oxidizing environments. Whereas stainless steels and titanium alloys are stable in an oxidizing environment.
8. Which of the following material is used for handling hydrogen peroxide?
a) Commercially pure metals
b) Alloys
c) Both commercially pure metal and alloys
d) Neither commercially pure metals nor alloys