G-CoCr28 Cobalt vs. SAE-AISI A8 Steel

G-CoCr28 cobalt belongs to the cobalt alloys classification, while SAE-AISI A8 steel belongs to the iron alloys. They have a modest 24% of their average alloy composition in common, which, by itself, doesn't mean much. There are 21 material properties with values for both materials. Properties with values for just one material (9, in this case) are not shown.

For each property being compared, the top bar is G-CoCr28 cobalt and the bottom bar is SAE-AISI A8 steel.

G-CoCr28 (2.4778) Cobalt-Chromium Alloy SAE-AISI A8 (T30108) Air-Hardening Steel

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa		210
Elastic (Young's, Tensile) Modulus, GPa		190

Poisson's Ratio		0.28
Poisson's Ratio		0.29

Shear Modulus, GPa		83
Shear Modulus, GPa		74

Tensile Strength: Ultimate (UTS), MPa		560
Tensile Strength: Ultimate (UTS), MPa		700 to 1920

Thermal Properties

Latent Heat of Fusion, J/g		320
Latent Heat of Fusion, J/g		270

Melting Completion (Liquidus), °C		1330
Melting Completion (Liquidus), °C		1480

Melting Onset (Solidus), °C		1270
Melting Onset (Solidus), °C		1430

Specific Heat Capacity, J/kg-K		470
Specific Heat Capacity, J/kg-K		470

Thermal Conductivity, W/m-K		8.5
Thermal Conductivity, W/m-K		37

Thermal Expansion, µm/m-K		14
Thermal Expansion, µm/m-K		12

Otherwise Unclassified Properties

Base Metal Price, % relative		100
Base Metal Price, % relative		8.5

Density, g/cm³		8.1
Density, g/cm³		7.9

Embodied Carbon, kg CO₂/kg material		6.2
Embodied Carbon, kg CO₂/kg material		2.3

Embodied Energy, MJ/kg		84
Embodied Energy, MJ/kg		31

Embodied Water, L/kg		440
Embodied Water, L/kg		73

Common Calculations

Stiffness to Weight: Axial, points		15
Stiffness to Weight: Axial, points		14

Stiffness to Weight: Bending, points		24
Stiffness to Weight: Bending, points		24

Strength to Weight: Axial, points		19
Strength to Weight: Axial, points		25 to 68

Strength to Weight: Bending, points		19
Strength to Weight: Bending, points		22 to 44

Thermal Diffusivity, mm²/s		2.2
Thermal Diffusivity, mm²/s		9.9

Thermal Shock Resistance, points		14
Thermal Shock Resistance, points		22 to 62

Alloy Composition

Carbon (C), %		0.050 to 0.25
Carbon (C), %		0.5 to 0.6

Chromium (Cr), %		27 to 30
Chromium (Cr), %		4.8 to 5.5

Cobalt (Co), %		48 to 52
Cobalt (Co), %		0

Copper (Cu), %		0
Copper (Cu), %		0 to 0.25

Iron (Fe), %		9.7 to 24.5
Iron (Fe), %		88.5 to 91.9

Manganese (Mn), %		0 to 1.5
Manganese (Mn), %		0 to 0.5

Molybdenum (Mo), %		0 to 0.5
Molybdenum (Mo), %		1.2 to 1.7

Nickel (Ni), %		0 to 4.0
Nickel (Ni), %		0 to 0.3

Niobium (Nb), %		0 to 0.5
Niobium (Nb), %		0

Phosphorus (P), %		0 to 0.040
Phosphorus (P), %		0 to 0.030

Silicon (Si), %		0.5 to 1.5
Silicon (Si), %		0.75 to 1.1

Sulfur (S), %		0 to 0.030
Sulfur (S), %		0 to 0.030

Tungsten (W), %		0
Tungsten (W), %		1.0 to 1.5