ASTM A387 Grade 21 Steel vs. AISI 431 Stainless Steel
Both ASTM A387 grade 21 steel and AISI 431 stainless steel are iron alloys. They have 85% of their average alloy composition in common. There are 32 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 steel and the bottom bar is AISI 431 stainless steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 150 to 180 | |
| 250 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 200 |
| Elongation at Break, % | 21 | |
| 15 to 17 |
| Fatigue Strength, MPa | 160 to 250 | |
| 430 to 610 |
| Poisson's Ratio | 0.29 | |
| 0.28 |
| Shear Modulus, GPa | 74 | |
| 77 |
| Shear Strength, MPa | 310 to 370 | |
| 550 to 840 |
| Tensile Strength: Ultimate (UTS), MPa | 500 to 590 | |
| 890 to 1380 |
| Tensile Strength: Yield (Proof), MPa | 230 to 350 | |
| 710 to 1040 |
Thermal Properties
| Latent Heat of Fusion, J/g | 260 | |
| 280 |
| Maximum Temperature: Mechanical, °C | 480 | |
| 850 |
| Melting Completion (Liquidus), °C | 1470 | |
| 1510 |
| Melting Onset (Solidus), °C | 1430 | |
| 1450 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 480 |
| Thermal Conductivity, W/m-K | 41 | |
| 26 |
| Thermal Expansion, µm/m-K | 13 | |
| 12 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.6 | |
| 2.6 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.8 | |
| 3.0 |
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 | |
| 16 |
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 84 to 110 | |
| 140 to 180 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 140 to 320 | |
| 1270 to 2770 |
| Stiffness to Weight: Axial, points | 13 | |
| 14 |
| Stiffness to Weight: Bending, points | 24 | |
| 25 |
| Strength to Weight: Axial, points | 18 to 21 | |
| 32 to 50 |
| Strength to Weight: Bending, points | 18 to 20 | |
| 27 to 36 |
| Thermal Diffusivity, mm2/s | 11 | |
| 7.0 |
| Thermal Shock Resistance, points | 14 to 17 | |
| 28 to 43 |
Alloy Composition
| Carbon (C), % | 0.050 to 0.15 | |
| 0 to 0.2 |
| Chromium (Cr), % | 2.8 to 3.3 | |
| 15 to 17 |
| Iron (Fe), % | 94.4 to 96 | |
| 78.2 to 83.8 |
| Manganese (Mn), % | 0.3 to 0.6 | |
| 0 to 1.0 |
| Molybdenum (Mo), % | 0.9 to 1.1 | |
| 0 |
| Nickel (Ni), % | 0 | |
| 1.3 to 2.5 |
| 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 0.030 |