AISI 440A Stainless Steel vs. ASTM A387 Grade 21 Steel
Both AISI 440A stainless steel and ASTM A387 grade 21 steel are iron alloys. They have 85% of their average alloy composition in common. There are 30 material properties with values for both materials. Properties with values for just one material (3, in this case) are not shown.
For each property being compared, the top bar is AISI 440A stainless steel and the bottom bar is ASTM A387 grade 21 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 200 | |
| 190 |
| Elongation at Break, % | 5.0 to 20 | |
| 21 |
| Fatigue Strength, MPa | 270 to 790 | |
| 160 to 250 |
| Poisson's Ratio | 0.28 | |
| 0.29 |
| Shear Modulus, GPa | 77 | |
| 74 |
| Shear Strength, MPa | 450 to 1040 | |
| 310 to 370 |
| Tensile Strength: Ultimate (UTS), MPa | 730 to 1790 | |
| 500 to 590 |
| Tensile Strength: Yield (Proof), MPa | 420 to 1650 | |
| 230 to 350 |
Thermal Properties
| Latent Heat of Fusion, J/g | 280 | |
| 260 |
| Maximum Temperature: Mechanical, °C | 760 | |
| 480 |
| Melting Completion (Liquidus), °C | 1480 | |
| 1470 |
| Melting Onset (Solidus), °C | 1370 | |
| 1430 |
| Specific Heat Capacity, J/kg-K | 480 | |
| 470 |
| Thermal Conductivity, W/m-K | 23 | |
| 41 |
| Thermal Expansion, µm/m-K | 10 | |
| 13 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 2.5 | |
| 7.6 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 2.9 | |
| 8.8 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 9.0 | |
| 4.1 |
| Density, g/cm3 | 7.7 | |
| 7.9 |
| Embodied Carbon, kg CO2/kg material | 2.2 | |
| 1.8 |
| Embodied Energy, MJ/kg | 31 | |
| 23 |
| Embodied Water, L/kg | 120 | |
| 62 |
Common Calculations
| PREN (Pitting Resistance) | 18 | |
| 6.4 |
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 87 to 120 | |
| 84 to 110 |
| Stiffness to Weight: Axial, points | 14 | |
| 13 |
| Stiffness to Weight: Bending, points | 25 | |
| 24 |
| Strength to Weight: Axial, points | 26 to 65 | |
| 18 to 21 |
| Strength to Weight: Bending, points | 23 to 43 | |
| 18 to 20 |
| Thermal Diffusivity, mm2/s | 6.2 | |
| 11 |
| Thermal Shock Resistance, points | 26 to 65 | |
| 14 to 17 |
Alloy Composition
| Carbon (C), % | 0.6 to 0.75 | |
| 0.050 to 0.15 |
| Chromium (Cr), % | 16 to 18 | |
| 2.8 to 3.3 |
| Iron (Fe), % | 78.4 to 83.4 | |
| 94.4 to 96 |
| Manganese (Mn), % | 0 to 1.0 | |
| 0.3 to 0.6 |
| Molybdenum (Mo), % | 0 to 0.75 | |
| 0.9 to 1.1 |
| Phosphorus (P), % | 0 to 0.040 | |
| 0 to 0.025 |
| Silicon (Si), % | 0 to 1.0 | |
| 0 to 0.5 |
| Sulfur (S), % | 0 to 0.015 | |
| 0 to 0.025 |