ASTM A387 Grade 21 Steel vs. AISI 309 Stainless Steel
Both ASTM A387 grade 21 steel and AISI 309 stainless steel are iron alloys. They have 66% 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 309 stainless steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 150 to 180 | |
| 180 to 210 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 200 |
| Elongation at Break, % | 21 | |
| 34 to 47 |
| Fatigue Strength, MPa | 160 to 250 | |
| 250 to 280 |
| Poisson's Ratio | 0.29 | |
| 0.27 |
| Shear Modulus, GPa | 74 | |
| 78 |
| Shear Strength, MPa | 310 to 370 | |
| 420 to 470 |
| Tensile Strength: Ultimate (UTS), MPa | 500 to 590 | |
| 600 to 710 |
| Tensile Strength: Yield (Proof), MPa | 230 to 350 | |
| 260 to 350 |
Thermal Properties
| Latent Heat of Fusion, J/g | 260 | |
| 290 |
| Maximum Temperature: Mechanical, °C | 480 | |
| 980 |
| Melting Completion (Liquidus), °C | 1470 | |
| 1450 |
| Melting Onset (Solidus), °C | 1430 | |
| 1400 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 480 |
| Thermal Conductivity, W/m-K | 41 | |
| 16 |
| Thermal Expansion, µm/m-K | 13 | |
| 15 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.6 | |
| 2.2 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.8 | |
| 2.5 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 4.1 | |
| 19 |
| Density, g/cm3 | 7.9 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 1.8 | |
| 3.6 |
| Embodied Energy, MJ/kg | 23 | |
| 51 |
| Embodied Water, L/kg | 62 | |
| 170 |
Common Calculations
| PREN (Pitting Resistance) | 6.4 | |
| 23 |
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 84 to 110 | |
| 200 to 230 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 140 to 320 | |
| 170 to 310 |
| Stiffness to Weight: Axial, points | 13 | |
| 14 |
| Stiffness to Weight: Bending, points | 24 | |
| 25 |
| Strength to Weight: Axial, points | 18 to 21 | |
| 21 to 25 |
| Strength to Weight: Bending, points | 18 to 20 | |
| 20 to 23 |
| Thermal Diffusivity, mm2/s | 11 | |
| 4.3 |
| Thermal Shock Resistance, points | 14 to 17 | |
| 14 to 16 |
Alloy Composition
| Carbon (C), % | 0.050 to 0.15 | |
| 0 to 0.2 |
| Chromium (Cr), % | 2.8 to 3.3 | |
| 22 to 24 |
| Iron (Fe), % | 94.4 to 96 | |
| 58 to 66 |
| Manganese (Mn), % | 0.3 to 0.6 | |
| 0 to 2.0 |
| Molybdenum (Mo), % | 0.9 to 1.1 | |
| 0 |
| Nickel (Ni), % | 0 | |
| 12 to 15 |
| Phosphorus (P), % | 0 to 0.025 | |
| 0 to 0.045 |
| Silicon (Si), % | 0 to 0.5 | |
| 0 to 0.75 |
| Sulfur (S), % | 0 to 0.025 | |
| 0 to 0.030 |