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ASTM Grade HI Steel vs. R30021 Cobalt

ASTM grade HI steel belongs to the iron alloys classification, while R30021 cobalt belongs to the cobalt alloys. They have a modest 33% 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 (7, in this case) are not shown.

For each property being compared, the top bar is ASTM grade HI steel and the bottom bar is R30021 cobalt.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 200
220
Elongation at Break, % 11
9.0
Fatigue Strength, MPa 150
250
Poisson's Ratio 0.27
0.29
Shear Modulus, GPa 79
86
Tensile Strength: Ultimate (UTS), MPa 550
700
Tensile Strength: Yield (Proof), MPa 270
500

Thermal Properties

Latent Heat of Fusion, J/g 310
330
Melting Completion (Liquidus), °C 1400
1350
Melting Onset (Solidus), °C 1350
1190
Specific Heat Capacity, J/kg-K 490
450
Thermal Conductivity, W/m-K 15
15
Thermal Expansion, µm/m-K 17
11

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 2.1
1.9
Electrical Conductivity: Equal Weight (Specific), % IACS 2.4
2.1

Otherwise Unclassified Properties

Density, g/cm3 7.8
8.4
Embodied Carbon, kg CO2/kg material 4.1
8.0
Embodied Energy, MJ/kg 59
110
Embodied Water, L/kg 200
520

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 52
57
Resilience: Unit (Modulus of Resilience), kJ/m3 180
570
Stiffness to Weight: Axial, points 14
15
Stiffness to Weight: Bending, points 25
24
Strength to Weight: Axial, points 20
23
Strength to Weight: Bending, points 19
21
Thermal Diffusivity, mm2/s 3.9
3.8
Thermal Shock Resistance, points 12
21

Alloy Composition

Carbon (C), % 0.2 to 0.5
0.2 to 0.35
Chromium (Cr), % 26 to 30
26 to 29
Cobalt (Co), % 0
61.7 to 67.3
Iron (Fe), % 46.9 to 59.8
0 to 3.0
Manganese (Mn), % 0 to 2.0
0
Molybdenum (Mo), % 0 to 0.5
4.5 to 6.0
Nickel (Ni), % 14 to 18
2.0 to 3.0
Phosphorus (P), % 0 to 0.040
0
Silicon (Si), % 0 to 2.0
0 to 1.5
Sulfur (S), % 0 to 0.040
0