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ASTM A372 Grade H Steel vs. SAE-AISI 4118 Steel

Both ASTM A372 grade H steel and SAE-AISI 4118 steel are iron alloys. Their average alloy composition is basically identical.

For each property being compared, the top bar is ASTM A372 grade H steel and the bottom bar is SAE-AISI 4118 steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 200 to 280
150
Elastic (Young's, Tensile) Modulus, GPa 190
190
Elongation at Break, % 20 to 22
23
Fatigue Strength, MPa 310 to 380
230
Poisson's Ratio 0.29
0.29
Shear Modulus, GPa 73
73
Shear Strength, MPa 410 to 570
320
Tensile Strength: Ultimate (UTS), MPa 650 to 910
500
Tensile Strength: Yield (Proof), MPa 430 to 550
320

Thermal Properties

Latent Heat of Fusion, J/g 250
250
Maximum Temperature: Mechanical, °C 410
410
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
46
Thermal Expansion, µm/m-K 13
13

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 7.2
7.2
Electrical Conductivity: Equal Weight (Specific), % IACS 8.3
8.2

Otherwise Unclassified Properties

Base Metal Price, % relative 2.3
2.3
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
49

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 130 to 160
100
Resilience: Unit (Modulus of Resilience), kJ/m3 500 to 810
280
Stiffness to Weight: Axial, points 13
13
Stiffness to Weight: Bending, points 24
24
Strength to Weight: Axial, points 23 to 32
18
Strength to Weight: Bending, points 21 to 27
18
Thermal Diffusivity, mm2/s 12
13
Thermal Shock Resistance, points 19 to 27
15

Alloy Composition

Carbon (C), % 0.3 to 0.4
0.18 to 0.23
Chromium (Cr), % 0.4 to 0.65
0.4 to 0.6
Iron (Fe), % 97.3 to 98.3
97.5 to 98.4
Manganese (Mn), % 0.75 to 1.1
0.7 to 0.9
Molybdenum (Mo), % 0.15 to 0.25
0.2 to 0.3
Phosphorus (P), % 0 to 0.015
0 to 0.035
Silicon (Si), % 0.15 to 0.35
0.15 to 0.35
Sulfur (S), % 0 to 0.010
0 to 0.040