ASTM A372 Grade H Class 70 vs. ASTM A372 Grade J Class 70
Both ASTM A372 grade H class 70 and ASTM A372 grade J class 70 are iron alloys. Both are furnished in the normalized and tempered condition. Their average alloy composition is basically identical.
For each property being compared, the top bar is ASTM A372 grade H class 70 and the bottom bar is ASTM A372 grade J class 70.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 280 | |
| 280 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 190 |
| Elongation at Break, % | 20 | |
| 20 |
| Fatigue Strength, MPa | 380 | |
| 380 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 73 | |
| 73 |
| Shear Strength, MPa | 570 | |
| 570 |
| Tensile Strength: Ultimate (UTS), MPa | 910 | |
| 910 |
| Tensile Strength: Yield (Proof), MPa | 550 | |
| 550 |
Thermal Properties
| Latent Heat of Fusion, J/g | 250 | |
| 250 |
| Maximum Temperature: Mechanical, °C | 410 | |
| 420 |
| Melting Completion (Liquidus), °C | 1460 | |
| 1460 |
| Melting Onset (Solidus), °C | 1420 | |
| 1420 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 470 |
| Thermal Conductivity, W/m-K | 45 | |
| 44 |
| Thermal Expansion, µm/m-K | 13 | |
| 13 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.2 | |
| 7.3 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.3 | |
| 8.4 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 2.3 | |
| 2.4 |
| Density, g/cm3 | 7.8 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 1.5 | |
| 1.5 |
| Embodied Energy, MJ/kg | 20 | |
| 20 |
| Embodied Water, L/kg | 49 | |
| 51 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 160 | |
| 160 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 810 | |
| 810 |
| Stiffness to Weight: Axial, points | 13 | |
| 13 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 |
| Strength to Weight: Axial, points | 32 | |
| 32 |
| Strength to Weight: Bending, points | 27 | |
| 27 |
| Thermal Diffusivity, mm2/s | 12 | |
| 12 |
| Thermal Shock Resistance, points | 27 | |
| 27 |
Alloy Composition
| Carbon (C), % | 0.3 to 0.4 | |
| 0.35 to 0.5 |
| Chromium (Cr), % | 0.4 to 0.65 | |
| 0.8 to 1.2 |
| Iron (Fe), % | 97.3 to 98.3 | |
| 96.7 to 97.8 |
| Manganese (Mn), % | 0.75 to 1.1 | |
| 0.75 to 1.1 |
| Molybdenum (Mo), % | 0.15 to 0.25 | |
| 0.15 to 0.25 |
| Phosphorus (P), % | 0 to 0.015 | |
| 0 to 0.015 |
| Silicon (Si), % | 0.15 to 0.35 | |
| 0.15 to 0.35 |
| Sulfur (S), % | 0 to 0.010 | |
| 0 to 0.010 |