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R30155 Cobalt vs. ASTM A387 Grade 21 Steel

Both R30155 cobalt and ASTM A387 grade 21 steel are iron alloys. They have a modest 35% of their average alloy composition in common, which, by itself, doesn't mean much. There are 30 material properties with values for both materials. Properties with values for just one material (4, in this case) are not shown.

For each property being compared, the top bar is R30155 cobalt and the bottom bar is ASTM A387 grade 21 steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 220
150 to 180
Elastic (Young's, Tensile) Modulus, GPa 210
190
Elongation at Break, % 34
21
Fatigue Strength, MPa 310
160 to 250
Poisson's Ratio 0.29
0.29
Shear Modulus, GPa 81
74
Shear Strength, MPa 570
310 to 370
Tensile Strength: Ultimate (UTS), MPa 850
500 to 590
Tensile Strength: Yield (Proof), MPa 390
230 to 350

Thermal Properties

Latent Heat of Fusion, J/g 300
260
Maximum Temperature: Mechanical, °C 1100
480
Melting Completion (Liquidus), °C 1470
1470
Melting Onset (Solidus), °C 1420
1430
Specific Heat Capacity, J/kg-K 450
470
Thermal Conductivity, W/m-K 12
41
Thermal Expansion, µm/m-K 14
13

Otherwise Unclassified Properties

Base Metal Price, % relative 80
4.1
Density, g/cm3 8.5
7.9
Embodied Carbon, kg CO2/kg material 9.7
1.8
Embodied Energy, MJ/kg 150
23
Embodied Water, L/kg 300
62

Common Calculations

PREN (Pitting Resistance) 37
6.4
Resilience: Ultimate (Unit Rupture Work), MJ/m3 230
84 to 110
Resilience: Unit (Modulus of Resilience), kJ/m3 370
140 to 320
Stiffness to Weight: Axial, points 14
13
Stiffness to Weight: Bending, points 23
24
Strength to Weight: Axial, points 28
18 to 21
Strength to Weight: Bending, points 24
18 to 20
Thermal Diffusivity, mm2/s 3.2
11
Thermal Shock Resistance, points 21
14 to 17

Alloy Composition

Carbon (C), % 0.080 to 0.16
0.050 to 0.15
Chromium (Cr), % 20 to 22.5
2.8 to 3.3
Cobalt (Co), % 18.5 to 21
0
Iron (Fe), % 24.3 to 36.2
94.4 to 96
Manganese (Mn), % 1.0 to 2.0
0.3 to 0.6
Molybdenum (Mo), % 2.5 to 3.5
0.9 to 1.1
Nickel (Ni), % 19 to 21
0
Niobium (Nb), % 0.75 to 1.3
0
Nitrogen (N), % 0 to 0.2
0
Phosphorus (P), % 0 to 0.040
0 to 0.025
Silicon (Si), % 0 to 1.0
0 to 0.5
Sulfur (S), % 0 to 0.030
0 to 0.025
Tantalum (Ta), % 0.75 to 1.3
0
Tungsten (W), % 2.0 to 3.0
0