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SAE-AISI 8740 Steel vs. R30008 Cobalt

SAE-AISI 8740 steel belongs to the iron alloys classification, while R30008 cobalt belongs to the cobalt alloys. There are 23 material properties with values for both materials. Properties with values for just one material (8, in this case) are not shown.

For each property being compared, the top bar is SAE-AISI 8740 steel and the bottom bar is R30008 cobalt.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 190
210
Elongation at Break, % 11 to 23
1.1 to 73
Fatigue Strength, MPa 270 to 350
320 to 530
Poisson's Ratio 0.29
0.29
Shear Modulus, GPa 73
83
Tensile Strength: Ultimate (UTS), MPa 580 to 670
950 to 1700
Tensile Strength: Yield (Proof), MPa 380 to 570
500 to 1080

Thermal Properties

Latent Heat of Fusion, J/g 250
320
Melting Completion (Liquidus), °C 1460
1400
Melting Onset (Solidus), °C 1420
1330
Specific Heat Capacity, J/kg-K 470
450
Thermal Expansion, µm/m-K 13
13

Otherwise Unclassified Properties

Base Metal Price, % relative 2.6
95
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
400

Common Calculations

Resilience: Unit (Modulus of Resilience), kJ/m3 390 to 850
590 to 2720
Stiffness to Weight: Axial, points 13
14
Stiffness to Weight: Bending, points 24
24
Strength to Weight: Axial, points 20 to 24
31 to 56
Strength to Weight: Bending, points 20 to 22
25 to 37
Thermal Shock Resistance, points 17 to 20
25 to 44

Alloy Composition

Boron (B), % 0
0 to 0.0010
Carbon (C), % 0.38 to 0.43
0 to 0.15
Chromium (Cr), % 0.4 to 0.6
18.5 to 21.5
Cobalt (Co), % 0
39 to 42
Iron (Fe), % 96.5 to 97.7
7.6 to 20
Manganese (Mn), % 0.75 to 1.0
1.0 to 2.0
Molybdenum (Mo), % 0.2 to 0.3
6.5 to 7.5
Nickel (Ni), % 0.4 to 0.7
15 to 18
Phosphorus (P), % 0 to 0.035
0 to 0.015
Silicon (Si), % 0.15 to 0.35
0 to 1.2
Sulfur (S), % 0 to 0.040
0 to 0.015

Comparable Variants