Corrosion Engineering Questions and Answers for Experienced people on “Principles – Metallurgical and Other Aspects”.
1. Which of the following are the types of materials, that are categorized based on its atomic arrangement?
a) Crystalline
b) Amorphous
c) Semi-crystalline
d) Crystalline, amorphous and semi-crystalline
Answer: d
Clarification: The atoms in the crystalline materials are regularly arranged with the same repeating unit in a long-range order. Examples of crystalline materials are metals.
The atoms in which the atoms are not regularly arranged over a long-range are called amorphous materials. Example: Glass, rubbers.
Whereas semi-crystalline is the combination of both crystalline and amorphous materials.
2. What is the crystal structure of Austenitic stainless steel?
a) Face centered cubic structure
b) Body-centered cubic structure
c) Hexagonal close packed structure
d) Simple cubic structure
Answer: a
Clarification: Austenitic stainless steel is an alloy of iron, chromium, and nickel. Due to the high content of chromium, the resultant stabilizes in the austenitic phase. Austenite usually exists in the FCC (Face centered cubic) crystal structure.
3. What is the crystal structure of Magnesium?
a) Face centered cubic structure
b) Body-centered cubic structure
c) Hexagonal close packed structure
d) Simple cubic structure
Answer: c
Clarification: HCP is abbreviated as hexagonal close packed structure. Conditions for HCP is a1=a2≠a3 and α=β=60, γ̈=120, where a1, a2, a3 are unit vectors in three directions and α, β, γ̈ are angles between them. Magnesium possesses an HCP crystal structure.
4. Which of the following crystal structure is depicted in the given figure?
a) Face centered cubic structure
b) Hexagonal close packed structure
c) Body-centered cubic structure
d) Simple cubic structure
Answer: c
Clarification: Simple cubic structure is a cube with lattice atoms only at the corners.
Face centered cubic structure is a cube with lattice atoms at the corners along with at the centers of cubic faces.
BCC is abbreviated as a Body-centered cubic structure. It is a cube with lattice atoms at the corner along with a single atom at the center of the cube.
5. Which of the following is/are the properties of metals?
a) Ductility
b) Electrical conductivity
c) Thermal conductivity
d) Ductility, electrical and thermal conductivity
Answer: d
Clarification:
Ductility, malleability, conductors of heat and electricity, lustrous, definite melting and boiling point, lustrous, high strength, sonorous, etc are the properties of metals.
6. Which of the following types of bonds are non-directional in nature?
a) Covalent bond
b) Ionic bond
c) Metallic bond
d) Covalent and metallic bond
Answer: d
Clarification: Non-directional bonding is a type in which each atom is bonded to many of its neighbors. Covalent and metallic bonds are non-directional in nature whereas ionic bond is directional in nature.
7. Grain boundaries are the mismatch regions formed between two grains during solidification.
a) True
b) False
Answer: a
Clarification: Every metal microstructure consists of grains and grain boundaries. Grain boundaries are high energy areas, formed due to the mismatch between the grains during the solidification.
8. Which of the following is an example of a homogenous alloy?
a) 18-8 stainless steel
b) Low carbon steel
c) High carbon steel
d) Spheroidal cast iron