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R30003 Cobalt vs. ASTM A387 Grade 21 Steel

R30003 cobalt belongs to the cobalt alloys classification, while ASTM A387 grade 21 steel belongs to the iron alloys. They have a modest 20% of their average alloy composition in common, which, by itself, doesn't mean much. 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 R30003 cobalt and the bottom bar is ASTM A387 grade 21 steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 210
190
Elongation at Break, % 10 to 73
21
Fatigue Strength, MPa 320 to 560
160 to 250
Poisson's Ratio 0.29
0.29
Shear Modulus, GPa 83
74
Tensile Strength: Ultimate (UTS), MPa 970 to 1720
500 to 590
Tensile Strength: Yield (Proof), MPa 510 to 1090
230 to 350

Thermal Properties

Latent Heat of Fusion, J/g 310
260
Melting Completion (Liquidus), °C 1400
1470
Melting Onset (Solidus), °C 1440
1430
Specific Heat Capacity, J/kg-K 450
470
Thermal Conductivity, W/m-K 13
41
Thermal Expansion, µm/m-K 13
13

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 2.0
7.6
Electrical Conductivity: Equal Weight (Specific), % IACS 2.1
8.8

Otherwise Unclassified Properties

Base Metal Price, % relative 95
4.1
Density, g/cm3 8.4
7.9
Embodied Carbon, kg CO2/kg material 8.0
1.8
Embodied Energy, MJ/kg 110
23
Embodied Water, L/kg 400
62

Common Calculations

Resilience: Unit (Modulus of Resilience), kJ/m3 600 to 2790
140 to 320
Stiffness to Weight: Axial, points 14
13
Stiffness to Weight: Bending, points 24
24
Strength to Weight: Axial, points 32 to 57
18 to 21
Strength to Weight: Bending, points 26 to 38
18 to 20
Thermal Diffusivity, mm2/s 3.3
11
Thermal Shock Resistance, points 26 to 45
14 to 17

Alloy Composition

Boron (B), % 0 to 0.1
0
Carbon (C), % 0 to 0.15
0.050 to 0.15
Chromium (Cr), % 19 to 21
2.8 to 3.3
Cobalt (Co), % 39 to 41
0
Iron (Fe), % 10 to 20.5
94.4 to 96
Manganese (Mn), % 1.5 to 2.5
0.3 to 0.6
Molybdenum (Mo), % 6.0 to 8.0
0.9 to 1.1
Nickel (Ni), % 14 to 16
0
Phosphorus (P), % 0 to 0.015
0 to 0.025
Silicon (Si), % 0 to 1.2
0 to 0.5
Sulfur (S), % 0 to 0.015
0 to 0.025

Comparable Variants