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R31538 Cobalt vs. R30021 Cobalt

Both R31538 cobalt and R30021 cobalt are cobalt alloys. They have a very high 98% of their average alloy composition in common. There are 28 material properties with values for both materials. Properties with values for just one material (2, in this case) are not shown.

For each property being compared, the top bar is R31538 cobalt and the bottom bar is R30021 cobalt.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 220
220
Elongation at Break, % 13 to 23
9.0
Fatigue Strength, MPa 310 to 480
250
Poisson's Ratio 0.29
0.29
Rockwell C Hardness 25 to 35
32
Shear Modulus, GPa 86
86
Tensile Strength: Ultimate (UTS), MPa 1020 to 1360
700
Tensile Strength: Yield (Proof), MPa 580 to 930
500

Thermal Properties

Latent Heat of Fusion, J/g 320
330
Melting Completion (Liquidus), °C 1360
1350
Melting Onset (Solidus), °C 1290
1190
Specific Heat Capacity, J/kg-K 450
450
Thermal Conductivity, W/m-K 13
15
Thermal Expansion, µm/m-K 13
11

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 2.0
1.9
Electrical Conductivity: Equal Weight (Specific), % IACS 2.1
2.1

Otherwise Unclassified Properties

Density, g/cm3 8.4
8.4
Embodied Carbon, kg CO2/kg material 8.1
8.0
Embodied Energy, MJ/kg 110
110
Embodied Water, L/kg 530
520

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 140 to 200
57
Resilience: Unit (Modulus of Resilience), kJ/m3 750 to 1920
570
Stiffness to Weight: Axial, points 15
15
Stiffness to Weight: Bending, points 24
24
Strength to Weight: Axial, points 34 to 45
23
Strength to Weight: Bending, points 27 to 32
21
Thermal Diffusivity, mm2/s 3.5
3.8
Thermal Shock Resistance, points 25 to 33
21

Alloy Composition

Carbon (C), % 0.15 to 0.35
0.2 to 0.35
Chromium (Cr), % 26 to 30
26 to 29
Cobalt (Co), % 58.7 to 68.9
61.7 to 67.3
Iron (Fe), % 0 to 0.75
0 to 3.0
Manganese (Mn), % 0 to 1.0
0
Molybdenum (Mo), % 5.0 to 7.0
4.5 to 6.0
Nickel (Ni), % 0 to 1.0
2.0 to 3.0
Nitrogen (N), % 0 to 0.25
0
Silicon (Si), % 0 to 1.0
0 to 1.5