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SAE-AISI 8740 Steel vs. R30075 Cobalt

SAE-AISI 8740 steel belongs to the iron alloys classification, while R30075 cobalt belongs to the cobalt alloys. There are 27 material properties with values for both materials. Properties with values for just one material (5, in this case) are not shown.

For each property being compared, the top bar is SAE-AISI 8740 steel and the bottom bar is R30075 cobalt.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 190
210 to 250
Elongation at Break, % 11 to 23
12
Fatigue Strength, MPa 270 to 350
250 to 840
Poisson's Ratio 0.29
0.29
Shear Modulus, GPa 73
82 to 98
Tensile Strength: Ultimate (UTS), MPa 580 to 670
780 to 1280
Tensile Strength: Yield (Proof), MPa 380 to 570
480 to 840

Thermal Properties

Latent Heat of Fusion, J/g 250
320
Melting Completion (Liquidus), °C 1460
1360
Melting Onset (Solidus), °C 1420
1290
Specific Heat Capacity, J/kg-K 470
450
Thermal Conductivity, W/m-K 39
13
Thermal Expansion, µm/m-K 13
12

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 7.3
2.0
Electrical Conductivity: Equal Weight (Specific), % IACS 8.4
2.1

Otherwise Unclassified Properties

Density, g/cm3 7.8
8.4
Embodied Carbon, kg CO2/kg material 1.5
8.1
Embodied Energy, MJ/kg 20
110
Embodied Water, L/kg 50
530

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 71 to 120
84 to 140
Resilience: Unit (Modulus of Resilience), kJ/m3 390 to 850
560 to 1410
Stiffness to Weight: Axial, points 13
14 to 17
Stiffness to Weight: Bending, points 24
24 to 25
Strength to Weight: Axial, points 20 to 24
26 to 42
Strength to Weight: Bending, points 20 to 22
22 to 31
Thermal Diffusivity, mm2/s 10
3.5
Thermal Shock Resistance, points 17 to 20
21 to 29

Alloy Composition

Aluminum (Al), % 0
0 to 0.1
Boron (B), % 0
0 to 0.010
Carbon (C), % 0.38 to 0.43
0 to 0.35
Chromium (Cr), % 0.4 to 0.6
27 to 30
Cobalt (Co), % 0
58.7 to 68
Iron (Fe), % 96.5 to 97.7
0 to 0.75
Manganese (Mn), % 0.75 to 1.0
0 to 1.0
Molybdenum (Mo), % 0.2 to 0.3
5.0 to 7.0
Nickel (Ni), % 0.4 to 0.7
0 to 0.5
Nitrogen (N), % 0
0 to 0.25
Phosphorus (P), % 0 to 0.035
0 to 0.020
Silicon (Si), % 0.15 to 0.35
0 to 1.0
Sulfur (S), % 0 to 0.040
0 to 0.010
Titanium (Ti), % 0
0 to 0.1
Tungsten (W), % 0
0 to 0.2

Comparable Variants