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S31655 Stainless Steel vs. R31538 Cobalt

S31655 stainless steel belongs to the iron alloys classification, while R31538 cobalt belongs to the cobalt alloys. They have a modest 24% 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 (9, in this case) are not shown.

For each property being compared, the top bar is S31655 stainless steel and the bottom bar is R31538 cobalt.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 200
220
Elongation at Break, % 39
13 to 23
Fatigue Strength, MPa 300
310 to 480
Poisson's Ratio 0.28
0.29
Shear Modulus, GPa 78
86
Tensile Strength: Ultimate (UTS), MPa 710
1020 to 1360
Tensile Strength: Yield (Proof), MPa 350
580 to 930

Thermal Properties

Latent Heat of Fusion, J/g 290
320
Melting Completion (Liquidus), °C 1430
1360
Melting Onset (Solidus), °C 1380
1290
Specific Heat Capacity, J/kg-K 480
450
Thermal Conductivity, W/m-K 15
13
Thermal Expansion, µm/m-K 16
13

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 2.4
2.0
Electrical Conductivity: Equal Weight (Specific), % IACS 2.7
2.1

Otherwise Unclassified Properties

Density, g/cm3 7.8
8.4
Embodied Carbon, kg CO2/kg material 3.3
8.1
Embodied Energy, MJ/kg 46
110
Embodied Water, L/kg 160
530

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 230
140 to 200
Resilience: Unit (Modulus of Resilience), kJ/m3 310
750 to 1920
Stiffness to Weight: Axial, points 14
15
Stiffness to Weight: Bending, points 25
24
Strength to Weight: Axial, points 25
34 to 45
Strength to Weight: Bending, points 23
27 to 32
Thermal Diffusivity, mm2/s 4.0
3.5
Thermal Shock Resistance, points 16
25 to 33

Alloy Composition

Carbon (C), % 0 to 0.030
0.15 to 0.35
Chromium (Cr), % 19.5 to 21.5
26 to 30
Cobalt (Co), % 0
58.7 to 68.9
Copper (Cu), % 0 to 1.0
0
Iron (Fe), % 63.2 to 71.9
0 to 0.75
Manganese (Mn), % 0 to 2.0
0 to 1.0
Molybdenum (Mo), % 0.5 to 1.5
5.0 to 7.0
Nickel (Ni), % 8.0 to 9.5
0 to 1.0
Nitrogen (N), % 0.14 to 0.25
0 to 0.25
Phosphorus (P), % 0 to 0.045
0
Silicon (Si), % 0 to 1.0
0 to 1.0
Sulfur (S), % 0 to 0.015
0