ASTM A387 Grade 21 Class 1 vs. Annealed AISI 440A
Both ASTM A387 grade 21 class 1 and annealed AISI 440A are iron alloys. Both are furnished in the annealed condition. They have 85% of their average alloy composition in common. There are 31 material properties with values for both materials. Properties with values for just one material (2, in this case) are not shown.
For each property being compared, the top bar is ASTM A387 grade 21 class 1 and the bottom bar is annealed AISI 440A.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 200 |
| Elongation at Break, % | 21 | |
| 20 |
| Fatigue Strength, MPa | 160 | |
| 270 |
| Poisson's Ratio | 0.29 | |
| 0.28 |
| Shear Modulus, GPa | 74 | |
| 77 |
| Shear Strength, MPa | 310 | |
| 450 |
| Tensile Strength: Ultimate (UTS), MPa | 500 | |
| 730 |
| Tensile Strength: Yield (Proof), MPa | 230 | |
| 420 |
Thermal Properties
| Latent Heat of Fusion, J/g | 260 | |
| 280 |
| Maximum Temperature: Mechanical, °C | 480 | |
| 760 |
| Melting Completion (Liquidus), °C | 1470 | |
| 1480 |
| Melting Onset (Solidus), °C | 1430 | |
| 1370 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 480 |
| Thermal Conductivity, W/m-K | 41 | |
| 23 |
| Thermal Expansion, µm/m-K | 13 | |
| 10 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.6 | |
| 2.5 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.8 | |
| 2.9 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 4.1 | |
| 9.0 |
| Density, g/cm3 | 7.9 | |
| 7.7 |
| Embodied Carbon, kg CO2/kg material | 1.8 | |
| 2.2 |
| Embodied Energy, MJ/kg | 23 | |
| 31 |
| Embodied Water, L/kg | 62 | |
| 120 |
Common Calculations
| PREN (Pitting Resistance) | 6.4 | |
| 18 |
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 84 | |
| 120 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 140 | |
| 440 |
| Stiffness to Weight: Axial, points | 13 | |
| 14 |
| Stiffness to Weight: Bending, points | 24 | |
| 25 |
| Strength to Weight: Axial, points | 18 | |
| 26 |
| Strength to Weight: Bending, points | 18 | |
| 23 |
| Thermal Diffusivity, mm2/s | 11 | |
| 6.2 |
| Thermal Shock Resistance, points | 14 | |
| 26 |
Alloy Composition
| Carbon (C), % | 0.050 to 0.15 | |
| 0.6 to 0.75 |
| Chromium (Cr), % | 2.8 to 3.3 | |
| 16 to 18 |
| Iron (Fe), % | 94.4 to 96 | |
| 78.4 to 83.4 |
| Manganese (Mn), % | 0.3 to 0.6 | |
| 0 to 1.0 |
| Molybdenum (Mo), % | 0.9 to 1.1 | |
| 0 to 0.75 |
| Phosphorus (P), % | 0 to 0.025 | |
| 0 to 0.040 |
| Silicon (Si), % | 0 to 0.5 | |
| 0 to 1.0 |
| Sulfur (S), % | 0 to 0.025 | |
| 0 to 0.015 |