ASTM A387 Grade 91 Class 2 vs. AISI 440A Stainless Steel
Both ASTM A387 grade 91 class 2 and AISI 440A stainless steel are iron alloys. They have a moderately high 91% 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 ASTM A387 grade 91 class 2 and the bottom bar is AISI 440A stainless steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 200 |
| Elongation at Break, % | 20 | |
| 5.0 to 20 |
| Fatigue Strength, MPa | 330 | |
| 270 to 790 |
| Poisson's Ratio | 0.28 | |
| 0.28 |
| Shear Modulus, GPa | 75 | |
| 77 |
| Shear Strength, MPa | 420 | |
| 450 to 1040 |
| Tensile Strength: Ultimate (UTS), MPa | 670 | |
| 730 to 1790 |
| Tensile Strength: Yield (Proof), MPa | 470 | |
| 420 to 1650 |
Thermal Properties
| Latent Heat of Fusion, J/g | 270 | |
| 280 |
| Maximum Temperature: Mechanical, °C | 600 | |
| 760 |
| Melting Completion (Liquidus), °C | 1460 | |
| 1480 |
| Melting Onset (Solidus), °C | 1420 | |
| 1370 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 480 |
| Thermal Conductivity, W/m-K | 26 | |
| 23 |
| Thermal Expansion, µm/m-K | 13 | |
| 10 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 8.9 | |
| 2.5 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 10 | |
| 2.9 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 7.0 | |
| 9.0 |
| Density, g/cm3 | 7.8 | |
| 7.7 |
| Embodied Carbon, kg CO2/kg material | 2.6 | |
| 2.2 |
| Embodied Energy, MJ/kg | 37 | |
| 31 |
| Embodied Water, L/kg | 88 | |
| 120 |
Common Calculations
| PREN (Pitting Resistance) | 13 | |
| 18 |
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 120 | |
| 87 to 120 |
| Stiffness to Weight: Axial, points | 14 | |
| 14 |
| Stiffness to Weight: Bending, points | 25 | |
| 25 |
| Strength to Weight: Axial, points | 24 | |
| 26 to 65 |
| Strength to Weight: Bending, points | 22 | |
| 23 to 43 |
| Thermal Diffusivity, mm2/s | 6.9 | |
| 6.2 |
| Thermal Shock Resistance, points | 19 | |
| 26 to 65 |
Alloy Composition
| Aluminum (Al), % | 0 to 0.020 | |
| 0 |
| Carbon (C), % | 0.080 to 0.12 | |
| 0.6 to 0.75 |
| Chromium (Cr), % | 8.0 to 9.5 | |
| 16 to 18 |
| Iron (Fe), % | 87.3 to 90.3 | |
| 78.4 to 83.4 |
| Manganese (Mn), % | 0.3 to 0.6 | |
| 0 to 1.0 |
| Molybdenum (Mo), % | 0.85 to 1.1 | |
| 0 to 0.75 |
| Nickel (Ni), % | 0 to 0.4 | |
| 0 |
| Niobium (Nb), % | 0.060 to 0.1 | |
| 0 |
| Nitrogen (N), % | 0.030 to 0.070 | |
| 0 |
| Phosphorus (P), % | 0 to 0.020 | |
| 0 to 0.040 |
| Silicon (Si), % | 0.2 to 0.5 | |
| 0 to 1.0 |
| Sulfur (S), % | 0 to 0.010 | |
| 0 to 0.015 |
| Titanium (Ti), % | 0 to 0.010 | |
| 0 |
| Vanadium (V), % | 0.18 to 0.25 | |
| 0 |
| Zirconium (Zr), % | 0 to 0.010 | |
| 0 |