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SAE-AISI 4340M Steel vs. SAE-AISI T8 Steel

Both SAE-AISI 4340M steel and SAE-AISI T8 steel are iron alloys. They have 75% of their average alloy composition in common. There are 22 material properties with values for both materials. Properties with values for just one material (13, in this case) are not shown.

For each property being compared, the top bar is SAE-AISI 4340M steel and the bottom bar is SAE-AISI T8 steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 190
200
Poisson's Ratio 0.29
0.29
Shear Modulus, GPa 72
78
Tensile Strength: Ultimate (UTS), MPa 2340
780 to 2140

Thermal Properties

Latent Heat of Fusion, J/g 280
250
Melting Completion (Liquidus), °C 1440
1730
Melting Onset (Solidus), °C 1400
1670
Specific Heat Capacity, J/kg-K 480
420
Thermal Conductivity, W/m-K 38
18
Thermal Expansion, µm/m-K 13
12

Otherwise Unclassified Properties

Base Metal Price, % relative 3.9
45
Density, g/cm3 7.8
9.0
Embodied Carbon, kg CO2/kg material 1.9
10
Embodied Energy, MJ/kg 26
160
Embodied Water, L/kg 55
120

Common Calculations

PREN (Pitting Resistance) 2.2
30
Stiffness to Weight: Axial, points 13
12
Stiffness to Weight: Bending, points 25
22
Strength to Weight: Axial, points 84
24 to 66
Strength to Weight: Bending, points 51
21 to 41
Thermal Diffusivity, mm2/s 10
4.8
Thermal Shock Resistance, points 70
24 to 66

Alloy Composition

Carbon (C), % 0.38 to 0.43
0.75 to 0.85
Chromium (Cr), % 0.7 to 1.0
3.8 to 4.5
Cobalt (Co), % 0
4.3 to 5.8
Copper (Cu), % 0
0 to 0.25
Iron (Fe), % 93.3 to 94.8
69.3 to 75.4
Manganese (Mn), % 0.65 to 0.9
0.2 to 0.4
Molybdenum (Mo), % 0.35 to 0.45
0.4 to 1.0
Nickel (Ni), % 1.7 to 2.0
0 to 0.3
Phosphorus (P), % 0 to 0.012
0 to 0.030
Silicon (Si), % 1.5 to 1.8
0.2 to 0.4
Sulfur (S), % 0 to 0.012
0 to 0.030
Tungsten (W), % 0
13.3 to 14.8
Vanadium (V), % 0.050 to 0.1
1.8 to 2.4