ASTM A387 Grade 91 Class 2 vs. AISI 321 Stainless Steel
Both ASTM A387 grade 91 class 2 and AISI 321 stainless steel are iron alloys. They have 80% of their average alloy composition in common. There are 32 material properties with values for both materials. Properties with values for just one material (1, 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 321 stainless steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 200 | |
| 170 to 210 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 200 |
| Elongation at Break, % | 20 | |
| 34 to 50 |
| Fatigue Strength, MPa | 330 | |
| 220 to 270 |
| Poisson's Ratio | 0.28 | |
| 0.28 |
| Shear Modulus, GPa | 75 | |
| 77 |
| Shear Strength, MPa | 420 | |
| 420 to 460 |
| Tensile Strength: Ultimate (UTS), MPa | 670 | |
| 590 to 690 |
| Tensile Strength: Yield (Proof), MPa | 470 | |
| 220 to 350 |
Thermal Properties
| Latent Heat of Fusion, J/g | 270 | |
| 290 |
| Maximum Temperature: Mechanical, °C | 600 | |
| 870 |
| Melting Completion (Liquidus), °C | 1460 | |
| 1430 |
| Melting Onset (Solidus), °C | 1420 | |
| 1400 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 480 |
| Thermal Conductivity, W/m-K | 26 | |
| 16 |
| Thermal Expansion, µm/m-K | 13 | |
| 17 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 8.9 | |
| 2.4 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 10 | |
| 2.7 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 7.0 | |
| 16 |
| Density, g/cm3 | 7.8 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 2.6 | |
| 3.2 |
| Embodied Energy, MJ/kg | 37 | |
| 45 |
| Embodied Water, L/kg | 88 | |
| 140 |
Common Calculations
| PREN (Pitting Resistance) | 13 | |
| 19 |
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 120 | |
| 190 to 230 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 580 | |
| 130 to 310 |
| Stiffness to Weight: Axial, points | 14 | |
| 14 |
| Stiffness to Weight: Bending, points | 25 | |
| 25 |
| Strength to Weight: Axial, points | 24 | |
| 21 to 25 |
| Strength to Weight: Bending, points | 22 | |
| 20 to 22 |
| Thermal Diffusivity, mm2/s | 6.9 | |
| 4.1 |
| Thermal Shock Resistance, points | 19 | |
| 13 to 15 |
Alloy Composition
| Aluminum (Al), % | 0 to 0.020 | |
| 0 |
| Carbon (C), % | 0.080 to 0.12 | |
| 0 to 0.080 |
| Chromium (Cr), % | 8.0 to 9.5 | |
| 17 to 19 |
| Iron (Fe), % | 87.3 to 90.3 | |
| 65.3 to 74 |
| Manganese (Mn), % | 0.3 to 0.6 | |
| 0 to 2.0 |
| Molybdenum (Mo), % | 0.85 to 1.1 | |
| 0 |
| Nickel (Ni), % | 0 to 0.4 | |
| 9.0 to 12 |
| Niobium (Nb), % | 0.060 to 0.1 | |
| 0 |
| Nitrogen (N), % | 0.030 to 0.070 | |
| 0 to 0.1 |
| Phosphorus (P), % | 0 to 0.020 | |
| 0 to 0.045 |
| Silicon (Si), % | 0.2 to 0.5 | |
| 0 to 0.75 |
| Sulfur (S), % | 0 to 0.010 | |
| 0 to 0.030 |
| Titanium (Ti), % | 0 to 0.010 | |
| 0 to 0.7 |
| Vanadium (V), % | 0.18 to 0.25 | |
| 0 |
| Zirconium (Zr), % | 0 to 0.010 | |
| 0 |