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