ASTM A229 Spring Steel vs. SAE-AISI 4621 Steel
Both ASTM A229 spring steel and SAE-AISI 4621 steel are iron alloys. They have a very high 98% of their average alloy composition in common.
For each property being compared, the top bar is ASTM A229 spring steel and the bottom bar is SAE-AISI 4621 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 490 to 550 | |
| 150 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 190 |
| Elongation at Break, % | 14 | |
| 27 |
| Fatigue Strength, MPa | 710 to 790 | |
| 270 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 72 | |
| 73 |
| Shear Strength, MPa | 1020 to 1140 | |
| 320 |
| Tensile Strength: Ultimate (UTS), MPa | 1690 to 1890 | |
| 500 |
| 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 | |
| 7.4 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.3 | |
| 8.4 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 1.8 | |
| 3.3 |
| Density, g/cm3 | 7.8 | |
| 7.9 |
| Embodied Carbon, kg CO2/kg material | 1.4 | |
| 1.6 |
| Embodied Energy, MJ/kg | 19 | |
| 22 |
| Embodied Water, L/kg | 46 | |
| 50 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 200 to 230 | |
| 120 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 3260 to 4080 | |
| 340 |
| Stiffness to Weight: Axial, points | 13 | |
| 13 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 |
| Strength to Weight: Axial, points | 60 to 67 | |
| 18 |
| Strength to Weight: Bending, points | 40 to 43 | |
| 18 |
| Thermal Diffusivity, mm2/s | 14 | |
| 12 |
| Thermal Shock Resistance, points | 54 to 60 | |
| 15 |
Alloy Composition
| Carbon (C), % | 0.55 to 0.85 | |
| 0.18 to 0.23 |
| Iron (Fe), % | 97.5 to 99 | |
| 96.1 to 97.1 |
| Manganese (Mn), % | 0.3 to 1.2 | |
| 0.7 to 0.9 |
| Molybdenum (Mo), % | 0 | |
| 0.2 to 0.3 |
| Nickel (Ni), % | 0 | |
| 1.7 to 2.0 |
| 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 |