Material property databases give you the typical values published by standards bodies and material suppliers. For design calculations, always use the minimum guaranteed values (often called A-basis or B-basis allowables), not the typical values — typical values are the average, and half of real material heats will fall below them.
The yield strength is the most important property for ductile metals in static loading. For brittle materials (cast iron, ceramics), use ultimate tensile strength with a higher factor of safety. For fatigue-critical parts, the endurance limit (typically 40–50% of UTS for steel) governs design.
Temperature matters significantly. Most published properties are at room temperature (20–25°C). Steel loses about 50% of its yield strength at 500°C. Aluminium alloys start softening above 150–200°C. Always check high-temperature properties if your component will see elevated temperatures in service.
Key Properties for Design
| Property | Symbol | Used For |
|---|
| Yield Strength | Sy | Static strength design |
| Ultimate Tensile Strength | Su / UTS | Failure prediction, fasteners |
| Young's Modulus | E | Deflection, stiffness |
| Endurance Limit | Se | Fatigue life |
| Fracture Toughness | KIC | Crack tolerance |