ASTM A369 Grade FP9 vs. ASTM A387 Grade 21L Class 1
Both ASTM A369 grade FP9 and ASTM A387 grade 21L class 1 are iron alloys. Both are furnished in the annealed condition. They have a moderately high 94% of their average alloy composition in common.
For each property being compared, the top bar is ASTM A369 grade FP9 and the bottom bar is ASTM A387 grade 21L class 1.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 140 | |
| 150 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 190 |
| Elongation at Break, % | 20 | |
| 21 |
| Fatigue Strength, MPa | 160 | |
| 160 |
| Poisson's Ratio | 0.28 | |
| 0.29 |
| Shear Modulus, GPa | 75 | |
| 74 |
| Shear Strength, MPa | 300 | |
| 310 |
| Tensile Strength: Ultimate (UTS), MPa | 470 | |
| 500 |
| Tensile Strength: Yield (Proof), MPa | 240 | |
| 230 |
Thermal Properties
| Latent Heat of Fusion, J/g | 270 | |
| 260 |
| Maximum Temperature: Mechanical, °C | 600 | |
| 480 |
| Melting Completion (Liquidus), °C | 1450 | |
| 1470 |
| Melting Onset (Solidus), °C | 1410 | |
| 1430 |
| Specific Heat Capacity, J/kg-K | 480 | |
| 470 |
| Thermal Conductivity, W/m-K | 26 | |
| 41 |
| Thermal Expansion, µm/m-K | 13 | |
| 13 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 9.0 | |
| 7.6 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 10 | |
| 8.8 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 6.5 | |
| 4.1 |
| Density, g/cm3 | 7.8 | |
| 7.9 |
| Embodied Carbon, kg CO2/kg material | 2.0 | |
| 1.8 |
| Embodied Energy, MJ/kg | 28 | |
| 23 |
| Embodied Water, L/kg | 87 | |
| 62 |
Common Calculations
| PREN (Pitting Resistance) | 12 | |
| 6.4 |
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 80 | |
| 84 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 140 | |
| 140 |
| Stiffness to Weight: Axial, points | 14 | |
| 13 |
| Stiffness to Weight: Bending, points | 25 | |
| 24 |
| Strength to Weight: Axial, points | 17 | |
| 18 |
| Strength to Weight: Bending, points | 17 | |
| 18 |
| Thermal Diffusivity, mm2/s | 6.9 | |
| 11 |
| Thermal Shock Resistance, points | 13 | |
| 14 |
Alloy Composition
| Carbon (C), % | 0 to 0.15 | |
| 0 to 0.1 |
| Chromium (Cr), % | 8.0 to 10 | |
| 2.8 to 3.3 |
| Iron (Fe), % | 87.1 to 90.3 | |
| 94.4 to 96.1 |
| Manganese (Mn), % | 0.3 to 0.6 | |
| 0.3 to 0.6 |
| Molybdenum (Mo), % | 0.9 to 1.1 | |
| 0.9 to 1.1 |
| Phosphorus (P), % | 0 to 0.030 | |
| 0 to 0.025 |
| Silicon (Si), % | 0.5 to 1.0 | |
| 0 to 0.5 |
| Sulfur (S), % | 0 to 0.030 | |
| 0 to 0.025 |