You are viewing first 10 short questions and answers that are usually asked during an interview on material science and engineering topic.
1. What is the difference between the isotropic and anisotropic materials ?
If a material exhibits same mechanical properties
regardless of loading direction, it is isotropic, e.g., homogeneous cast materials. Materials lacking this property are anisotropic.
2. What are orthotropic materials ?
Orthotropic materials are a special class of isotropic materials which can be described by giving their properties in three perpendicular directions e.g. wood; composites.
3. A plain carbon steel has Brinell Hardness Number (BHN) of 180. What are the values of Rc, VHN and ultimate strength ?
Rc = BHN/10 = 18, VHN = BHN = 180
Ultimate strength = 3.48 × BHN MPa = 620 MPa.
4. What properties are needed to be considered for application calling for following requirements:
ii) Strength of no plastic deformation under static load
iii) Strength to withstand overload without fracture
i) Reliability – elastic modulus and yield strength.
ii) Strength (for no plastic deformation under static loading) – yield point.
iii) Strength (overload) – Toughness and impact resistance.
iv) Wear resistance – Hardness
v) Reliability and safety – Endurance limit and yield.
5. Explain the effects of alloying chromium and nickel in stainless steel.
The addition of nickel and chromium increases the tensile strength and increase in resistance to corrosion takes place.
6. Mention two types of dislocations.
Dislocation refers to a break in the continuity of the lattice. In an edge dislocation, one plane of atoms gets squeezed out. In screw dislocation, the lattice atoms move from their regular ideal positions.
7. What are the principal constituents of brass ?
Principal constituents of brass are copper and zinc.
8. What is Curie point ?
Curie point is the temperature at which ferromagnetic materials can no longer be magnetized by outside forces.
9. Specific strength of materials is very high when they are in fibre size but lower when they are in bar form - Why ?
The crystal structure has ordered, repeating arrangement of atoms. Fibres are liable to maintain this and thus have high specific strength. As for size increases, the condition of ordered and repeating arrangements can’t be guaranteed because of several types of defects and dislocations, and thus the specific strength gets lower.
10. What is the percentage of carbon in cast iron ?