ASTM A229 Spring Steel vs. SAE-AISI 50B44 Steel
Both ASTM A229 spring steel and SAE-AISI 50B44 steel are iron alloys. Their average alloy composition is basically identical.
For each property being compared, the top bar is ASTM A229 spring steel and the bottom bar is SAE-AISI 50B44 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 490 to 550 | |
| 170 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 190 |
| Elongation at Break, % | 14 | |
| 22 |
| Fatigue Strength, MPa | 710 to 790 | |
| 250 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 72 | |
| 73 |
| Shear Strength, MPa | 1020 to 1140 | |
| 360 |
| Tensile Strength: Ultimate (UTS), MPa | 1690 to 1890 | |
| 570 |
| Tensile Strength: Yield (Proof), MPa | 1100 to 1230 | |
| 360 |
Thermal Properties
| Latent Heat of Fusion, J/g | 250 | |
| 250 |
| Maximum Temperature: Mechanical, °C | 400 | |
| 410 |
| Melting Completion (Liquidus), °C | 1450 | |
| 1460 |
| Melting Onset (Solidus), °C | 1410 | |
| 1420 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 470 |
| Thermal Conductivity, W/m-K | 50 | |
| 46 |
| Thermal Expansion, µm/m-K | 12 | |
| 13 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.2 | |
| 7.2 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.3 | |
| 8.2 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 1.8 | |
| 2.0 |
| Density, g/cm3 | 7.8 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 1.4 | |
| 1.4 |
| Embodied Energy, MJ/kg | 19 | |
| 19 |
| Embodied Water, L/kg | 46 | |
| 48 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 200 to 230 | |
| 110 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 3260 to 4080 | |
| 350 |
| Stiffness to Weight: Axial, points | 13 | |
| 13 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 |
| Strength to Weight: Axial, points | 60 to 67 | |
| 20 |
| Strength to Weight: Bending, points | 40 to 43 | |
| 20 |
| Thermal Diffusivity, mm2/s | 14 | |
| 12 |
| Thermal Shock Resistance, points | 54 to 60 | |
| 17 |
Alloy Composition
| Boron (B), % | 0 | |
| 0.00050 to 0.0030 |
| Carbon (C), % | 0.55 to 0.85 | |
| 0.43 to 0.48 |
| Chromium (Cr), % | 0 | |
| 0.2 to 0.6 |
| Iron (Fe), % | 97.5 to 99 | |
| 97.5 to 98.5 |
| Manganese (Mn), % | 0.3 to 1.2 | |
| 0.75 to 1.0 |
| Phosphorus (P), % | 0 to 0.040 | |
| 0 to 0.035 |
| Silicon (Si), % | 0.15 to 0.35 | |
| 0.15 to 0.35 |
| Sulfur (S), % | 0 to 0.050 | |
| 0 to 0.040 |