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SAE-AISI D7 Steel vs. R30021 Cobalt

SAE-AISI D7 steel belongs to the iron alloys classification, while R30021 cobalt belongs to the cobalt alloys. There are 20 material properties with values for both materials. Properties with values for just one material (11, in this case) are not shown.

For each property being compared, the top bar is SAE-AISI D7 steel and the bottom bar is R30021 cobalt.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 190
220
Poisson's Ratio 0.28
0.29
Shear Modulus, GPa 73
86
Tensile Strength: Ultimate (UTS), MPa 800 to 2120
700

Thermal Properties

Latent Heat of Fusion, J/g 270
330
Melting Completion (Liquidus), °C 1440
1350
Melting Onset (Solidus), °C 1400
1190
Specific Heat Capacity, J/kg-K 480
450
Thermal Conductivity, W/m-K 27
15
Thermal Expansion, µm/m-K 11
11

Otherwise Unclassified Properties

Density, g/cm3 7.6
8.4
Embodied Carbon, kg CO2/kg material 11
8.0
Embodied Energy, MJ/kg 180
110
Embodied Water, L/kg 130
520

Common Calculations

Stiffness to Weight: Axial, points 14
15
Stiffness to Weight: Bending, points 25
24
Strength to Weight: Axial, points 29 to 78
23
Strength to Weight: Bending, points 25 to 48
21
Thermal Diffusivity, mm2/s 7.4
3.8
Thermal Shock Resistance, points 27 to 72
21

Alloy Composition

Carbon (C), % 2.2 to 2.5
0.2 to 0.35
Chromium (Cr), % 11.5 to 13.5
26 to 29
Cobalt (Co), % 0
61.7 to 67.3
Copper (Cu), % 0 to 0.25
0
Iron (Fe), % 76.6 to 81.9
0 to 3.0
Manganese (Mn), % 0 to 0.6
0
Molybdenum (Mo), % 0.7 to 1.2
4.5 to 6.0
Nickel (Ni), % 0 to 0.3
2.0 to 3.0
Phosphorus (P), % 0 to 0.030
0
Silicon (Si), % 0 to 0.6
0 to 1.5
Sulfur (S), % 0 to 0.030
0
Vanadium (V), % 3.8 to 4.4
0