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SAE-AISI 4720 Steel vs. ASTM A372 Grade B Steel

Both SAE-AISI 4720 steel and ASTM A372 grade B steel are iron alloys. They have a very high 98% of their average alloy composition in common.

For each property being compared, the top bar is SAE-AISI 4720 steel and the bottom bar is ASTM A372 grade B steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 150
180
Elastic (Young's, Tensile) Modulus, GPa 190
190
Elongation at Break, % 25
20
Fatigue Strength, MPa 260
240
Poisson's Ratio 0.29
0.29
Shear Modulus, GPa 73
73
Shear Strength, MPa 310
380
Tensile Strength: Ultimate (UTS), MPa 490
600
Tensile Strength: Yield (Proof), MPa 350
350

Thermal Properties

Latent Heat of Fusion, J/g 250
250
Maximum Temperature: Mechanical, °C 410
400
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 39
52
Thermal Expansion, µm/m-K 13
12

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 7.3
7.1
Electrical Conductivity: Equal Weight (Specific), % IACS 8.4
8.2

Otherwise Unclassified Properties

Base Metal Price, % relative 2.9
1.8
Density, g/cm3 7.9
7.8
Embodied Carbon, kg CO2/kg material 1.6
1.4
Embodied Energy, MJ/kg 21
18
Embodied Water, L/kg 50
46

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 110
100
Resilience: Unit (Modulus of Resilience), kJ/m3 330
330
Stiffness to Weight: Axial, points 13
13
Stiffness to Weight: Bending, points 24
24
Strength to Weight: Axial, points 17
21
Strength to Weight: Bending, points 18
20
Thermal Diffusivity, mm2/s 10
14
Thermal Shock Resistance, points 14
19

Alloy Composition

Carbon (C), % 0.17 to 0.22
0 to 0.35
Chromium (Cr), % 0.35 to 0.55
0
Iron (Fe), % 96.7 to 97.8
97.9 to 99.85
Manganese (Mn), % 0.5 to 0.7
0 to 1.4
Molybdenum (Mo), % 0.15 to 0.25
0
Nickel (Ni), % 0.9 to 1.2
0
Phosphorus (P), % 0 to 0.035
0 to 0.015
Silicon (Si), % 0.15 to 0.35
0.15 to 0.35
Sulfur (S), % 0 to 0.040
0 to 0.010