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R31538 Cobalt vs. S31730 Stainless Steel

R31538 cobalt belongs to the cobalt alloys classification, while S31730 stainless steel belongs to the iron alloys. They have a modest 23% of their average alloy composition in common, which, by itself, doesn't mean much. There are 23 material properties with values for both materials. Properties with values for just one material (13, in this case) are not shown.

For each property being compared, the top bar is R31538 cobalt and the bottom bar is S31730 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 220
200
Elongation at Break, % 13 to 23
40
Fatigue Strength, MPa 310 to 480
170
Poisson's Ratio 0.29
0.28
Shear Modulus, GPa 86
77
Tensile Strength: Ultimate (UTS), MPa 1020 to 1360
540
Tensile Strength: Yield (Proof), MPa 580 to 930
200

Thermal Properties

Latent Heat of Fusion, J/g 320
290
Melting Completion (Liquidus), °C 1360
1430
Melting Onset (Solidus), °C 1290
1390
Specific Heat Capacity, J/kg-K 450
470
Thermal Expansion, µm/m-K 13
16

Otherwise Unclassified Properties

Density, g/cm3 8.4
8.0
Embodied Carbon, kg CO2/kg material 8.1
4.6
Embodied Energy, MJ/kg 110
63
Embodied Water, L/kg 530
180

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 140 to 200
170
Resilience: Unit (Modulus of Resilience), kJ/m3 750 to 1920
99
Stiffness to Weight: Axial, points 15
14
Stiffness to Weight: Bending, points 24
24
Strength to Weight: Axial, points 34 to 45
19
Strength to Weight: Bending, points 27 to 32
18
Thermal Shock Resistance, points 25 to 33
12

Alloy Composition

Carbon (C), % 0.15 to 0.35
0 to 0.030
Chromium (Cr), % 26 to 30
17 to 19
Cobalt (Co), % 58.7 to 68.9
0
Copper (Cu), % 0
4.0 to 5.0
Iron (Fe), % 0 to 0.75
52.4 to 61
Manganese (Mn), % 0 to 1.0
0 to 2.0
Molybdenum (Mo), % 5.0 to 7.0
3.0 to 4.0
Nickel (Ni), % 0 to 1.0
15 to 16.5
Nitrogen (N), % 0 to 0.25
0 to 0.045
Phosphorus (P), % 0
0 to 0.040
Silicon (Si), % 0 to 1.0
0 to 1.0
Sulfur (S), % 0
0 to 0.010