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R31538 Cobalt vs. S44800 Stainless Steel

R31538 cobalt belongs to the cobalt alloys classification, while S44800 stainless steel belongs to the iron alloys. They have a modest 33% of their average alloy composition in common, which, by itself, doesn't mean much. There are 29 material properties with values for both materials. Properties with values for just one material (6, in this case) are not shown.

For each property being compared, the top bar is R31538 cobalt and the bottom bar is S44800 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 220
210
Elongation at Break, % 13 to 23
23
Fatigue Strength, MPa 310 to 480
300
Poisson's Ratio 0.29
0.27
Reduction in Area, % 13 to 22
45
Rockwell C Hardness 25 to 35
18
Shear Modulus, GPa 86
82
Tensile Strength: Ultimate (UTS), MPa 1020 to 1360
590
Tensile Strength: Yield (Proof), MPa 580 to 930
450

Thermal Properties

Latent Heat of Fusion, J/g 320
300
Melting Completion (Liquidus), °C 1360
1460
Melting Onset (Solidus), °C 1290
1410
Specific Heat Capacity, J/kg-K 450
480
Thermal Conductivity, W/m-K 13
17
Thermal Expansion, µm/m-K 13
11

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 2.0
2.6
Electrical Conductivity: Equal Weight (Specific), % IACS 2.1
3.0

Otherwise Unclassified Properties

Density, g/cm3 8.4
7.8
Embodied Carbon, kg CO2/kg material 8.1
3.8
Embodied Energy, MJ/kg 110
52
Embodied Water, L/kg 530
190

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 140 to 200
120
Resilience: Unit (Modulus of Resilience), kJ/m3 750 to 1920
480
Stiffness to Weight: Axial, points 15
15
Stiffness to Weight: Bending, points 24
25
Strength to Weight: Axial, points 34 to 45
21
Strength to Weight: Bending, points 27 to 32
20
Thermal Diffusivity, mm2/s 3.5
4.6
Thermal Shock Resistance, points 25 to 33
19

Alloy Composition

Carbon (C), % 0.15 to 0.35
0 to 0.010
Chromium (Cr), % 26 to 30
28 to 30
Cobalt (Co), % 58.7 to 68.9
0
Copper (Cu), % 0
0 to 0.15
Iron (Fe), % 0 to 0.75
62.6 to 66.5
Manganese (Mn), % 0 to 1.0
0 to 0.3
Molybdenum (Mo), % 5.0 to 7.0
3.5 to 4.2
Nickel (Ni), % 0 to 1.0
2.0 to 2.5
Nitrogen (N), % 0 to 0.25
0 to 0.020
Phosphorus (P), % 0
0 to 0.025
Silicon (Si), % 0 to 1.0
0 to 0.2
Sulfur (S), % 0
0 to 0.020