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SAE-AISI 4340 Steel vs. ASTM A356 Grade 8

Both SAE-AISI 4340 steel and ASTM A356 grade 8 are iron alloys. They have a very high 98% of their average alloy composition in common. There are 30 material properties with values for both materials. Properties with values for just one material (3, in this case) are not shown.

For each property being compared, the top bar is SAE-AISI 4340 steel and the bottom bar is ASTM A356 grade 8.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 210 to 360
190
Elastic (Young's, Tensile) Modulus, GPa 190
190
Elongation at Break, % 12 to 22
21
Fatigue Strength, MPa 330 to 740
270
Poisson's Ratio 0.29
0.29
Shear Modulus, GPa 73
73
Tensile Strength: Ultimate (UTS), MPa 690 to 1280
630
Tensile Strength: Yield (Proof), MPa 470 to 1150
390

Thermal Properties

Latent Heat of Fusion, J/g 250
260
Maximum Temperature: Mechanical, °C 430
440
Melting Completion (Liquidus), °C 1460
1470
Melting Onset (Solidus), °C 1420
1430
Specific Heat Capacity, J/kg-K 470
470
Thermal Conductivity, W/m-K 44
38
Thermal Expansion, µm/m-K 13
13

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 7.5
7.5
Electrical Conductivity: Equal Weight (Specific), % IACS 8.6
8.6

Otherwise Unclassified Properties

Base Metal Price, % relative 3.5
3.5
Density, g/cm3 7.8
7.8
Embodied Carbon, kg CO2/kg material 1.7
2.0
Embodied Energy, MJ/kg 22
26
Embodied Water, L/kg 53
55

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 79 to 170
110
Resilience: Unit (Modulus of Resilience), kJ/m3 590 to 3490
390
Stiffness to Weight: Axial, points 13
13
Stiffness to Weight: Bending, points 24
24
Strength to Weight: Axial, points 24 to 45
22
Strength to Weight: Bending, points 22 to 33
21
Thermal Diffusivity, mm2/s 12
10
Thermal Shock Resistance, points 20 to 38
18

Alloy Composition

Carbon (C), % 0.38 to 0.43
0 to 0.2
Chromium (Cr), % 0.7 to 0.9
1.0 to 1.5
Iron (Fe), % 95.1 to 96.3
95.4 to 97.4
Manganese (Mn), % 0.6 to 0.8
0.5 to 0.9
Molybdenum (Mo), % 0.2 to 0.3
0.9 to 1.2
Nickel (Ni), % 1.7 to 2.0
0
Phosphorus (P), % 0 to 0.035
0 to 0.035
Silicon (Si), % 0.15 to 0.35
0.2 to 0.6
Sulfur (S), % 0 to 0.040
0 to 0.030
Vanadium (V), % 0
0.050 to 0.15