ASTM A369 Grade FP21 vs. ASTM A387 Grade 9 Steel
Both ASTM A369 grade FP21 and ASTM A387 grade 9 steel are iron alloys. 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 FP21 and the bottom bar is ASTM A387 grade 9 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 140 | |
| 150 to 180 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 190 |
| Elongation at Break, % | 20 | |
| 20 to 21 |
| Fatigue Strength, MPa | 160 | |
| 160 to 240 |
| Poisson's Ratio | 0.29 | |
| 0.28 |
| Shear Modulus, GPa | 74 | |
| 75 |
| Shear Strength, MPa | 300 | |
| 310 to 380 |
| Tensile Strength: Ultimate (UTS), MPa | 470 | |
| 500 to 600 |
| Tensile Strength: Yield (Proof), MPa | 240 | |
| 230 to 350 |
Thermal Properties
| Latent Heat of Fusion, J/g | 260 | |
| 270 |
| Maximum Temperature: Mechanical, °C | 470 | |
| 600 |
| Melting Completion (Liquidus), °C | 1470 | |
| 1460 |
| Melting Onset (Solidus), °C | 1430 | |
| 1410 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 470 |
| Thermal Conductivity, W/m-K | 41 | |
| 26 |
| Thermal Expansion, µm/m-K | 13 | |
| 13 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.7 | |
| 9.0 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.8 | |
| 10 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 4.0 | |
| 6.5 |
| Density, g/cm3 | 7.8 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 1.8 | |
| 2.1 |
| Embodied Energy, MJ/kg | 23 | |
| 28 |
| Embodied Water, L/kg | 61 | |
| 87 |
Common Calculations
| PREN (Pitting Resistance) | 6.2 | |
| 12 |
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 80 | |
| 83 to 110 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 150 | |
| 140 to 310 |
| Stiffness to Weight: Axial, points | 13 | |
| 14 |
| Stiffness to Weight: Bending, points | 24 | |
| 25 |
| Strength to Weight: Axial, points | 17 | |
| 18 to 21 |
| Strength to Weight: Bending, points | 17 | |
| 18 to 20 |
| Thermal Diffusivity, mm2/s | 11 | |
| 6.9 |
| Thermal Shock Resistance, points | 14 | |
| 14 to 17 |
Alloy Composition
| Carbon (C), % | 0.050 to 0.15 | |
| 0 to 0.15 |
| Chromium (Cr), % | 2.7 to 3.4 | |
| 8.0 to 10 |
| Iron (Fe), % | 94.3 to 96.2 | |
| 87.1 to 90.8 |
| Manganese (Mn), % | 0.3 to 0.6 | |
| 0.3 to 0.6 |
| Molybdenum (Mo), % | 0.8 to 1.1 | |
| 0.9 to 1.1 |
| Phosphorus (P), % | 0 to 0.025 | |
| 0 to 0.025 |
| Silicon (Si), % | 0 to 0.5 | |
| 0 to 1.0 |
| Sulfur (S), % | 0 to 0.025 | |
| 0 to 0.025 |
| Vanadium (V), % | 0 | |
| 0 to 0.040 |