Reviewer for Materials Engineering in the Mechanical Engineering board.
1
Material Properties
| Property | Meaning |
|---|---|
| Strength | Resistance to load |
| Hardness | Resistance to scratching |
| Ductility | Ability to stretch |
| Toughness | Energy absorbed before fracture |
| Elasticity | Returns to shape |
2
Stress and Strain
Stress = Force รท Area | Strain = ฮL รท L
Within the elastic limit, stress is proportional to strain (Hooke’s Law).
โ ๏ธ Common Mistake
Beyond the elastic limit the material deforms permanently (plastic deformation) โ it will not return to shape.
3
Heat Treatment
Processes like annealing, quenching, and tempering change a metal’s hardness and strength.
4
Stress-Strain Curve
Key points: proportional limit โ elastic limit โ yield point โ ultimate strength โ fracture. Up to the elastic limit, deformation is recoverable.
๐ Quick Recap โ Master These
Before your exam, make sure you can confidently explain and apply each of the following:
- Material Properties
- Stress and Strain
- Heat Treatment
- Stress-Strain Curve
Re-read any section above where you hesitate.