5251 Aluminum vs. ASTM A229 Spring Steel
5251 aluminum belongs to the aluminum alloys classification, while ASTM A229 spring steel belongs to the iron alloys. Please note that the two materials have significantly dissimilar densities. This means that additional care is required when interpreting the data, because some material properties are based on units of mass, while others are based on units of area or volume.
For each property being compared, the top bar is 5251 aluminum and the bottom bar is ASTM A229 spring steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 44 to 79 | |
| 490 to 550 |
| Elastic (Young's, Tensile) Modulus, GPa | 68 | |
| 190 |
| Elongation at Break, % | 2.0 to 19 | |
| 14 |
| Fatigue Strength, MPa | 59 to 110 | |
| 710 to 790 |
| Poisson's Ratio | 0.33 | |
| 0.29 |
| Shear Modulus, GPa | 26 | |
| 72 |
| Shear Strength, MPa | 110 to 160 | |
| 1020 to 1140 |
| Tensile Strength: Ultimate (UTS), MPa | 180 to 280 | |
| 1690 to 1890 |
| Tensile Strength: Yield (Proof), MPa | 67 to 250 | |
| 1100 to 1230 |
Thermal Properties
| Latent Heat of Fusion, J/g | 400 | |
| 250 |
| Maximum Temperature: Mechanical, °C | 180 | |
| 400 |
| Melting Completion (Liquidus), °C | 650 | |
| 1450 |
| Melting Onset (Solidus), °C | 610 | |
| 1410 |
| Specific Heat Capacity, J/kg-K | 900 | |
| 470 |
| Thermal Conductivity, W/m-K | 150 | |
| 50 |
| Thermal Expansion, µm/m-K | 24 | |
| 12 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 37 | |
| 7.2 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 120 | |
| 8.3 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 9.5 | |
| 1.8 |
| Density, g/cm3 | 2.7 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 8.5 | |
| 1.4 |
| Embodied Energy, MJ/kg | 150 | |
| 19 |
| Embodied Water, L/kg | 1180 | |
| 46 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 5.4 to 27 | |
| 200 to 230 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 33 to 450 | |
| 3260 to 4080 |
| Stiffness to Weight: Axial, points | 14 | |
| 13 |
| Stiffness to Weight: Bending, points | 50 | |
| 24 |
| Strength to Weight: Axial, points | 18 to 29 | |
| 60 to 67 |
| Strength to Weight: Bending, points | 26 to 35 | |
| 40 to 43 |
| Thermal Diffusivity, mm2/s | 61 | |
| 14 |
| Thermal Shock Resistance, points | 7.9 to 13 | |
| 54 to 60 |
Alloy Composition
| Aluminum (Al), % | 95.5 to 98.2 | |
| 0 |
| Carbon (C), % | 0 | |
| 0.55 to 0.85 |
| Chromium (Cr), % | 0 to 0.15 | |
| 0 |
| Copper (Cu), % | 0 to 0.15 | |
| 0 |
| Iron (Fe), % | 0 to 0.5 | |
| 97.5 to 99 |
| Magnesium (Mg), % | 1.7 to 2.4 | |
| 0 |
| Manganese (Mn), % | 0.1 to 0.5 | |
| 0.3 to 1.2 |
| Phosphorus (P), % | 0 | |
| 0 to 0.040 |
| Silicon (Si), % | 0 to 0.4 | |
| 0.15 to 0.35 |
| Sulfur (S), % | 0 | |
| 0 to 0.050 |
| Titanium (Ti), % | 0 to 0.15 | |
| 0 |
| Zinc (Zn), % | 0 to 0.15 | |
| 0 |
| Residuals, % | 0 to 0.15 | |
| 0 |