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SAE-AISI 4340M Steel vs. G-CoCr28 Cobalt

SAE-AISI 4340M steel belongs to the iron alloys classification, while G-CoCr28 cobalt belongs to the cobalt alloys. They have a modest 22% 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 (8, in this case) are not shown.

For each property being compared, the top bar is SAE-AISI 4340M steel and the bottom bar is G-CoCr28 cobalt.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 190
210
Elongation at Break, % 6.0
6.7
Fatigue Strength, MPa 690
130
Poisson's Ratio 0.29
0.28
Shear Modulus, GPa 72
83
Tensile Strength: Ultimate (UTS), MPa 2340
560
Tensile Strength: Yield (Proof), MPa 1240
260

Thermal Properties

Latent Heat of Fusion, J/g 280
320
Maximum Temperature: Mechanical, °C 430
1200
Melting Completion (Liquidus), °C 1440
1330
Melting Onset (Solidus), °C 1400
1270
Specific Heat Capacity, J/kg-K 480
470
Thermal Conductivity, W/m-K 38
8.5
Thermal Expansion, µm/m-K 13
14

Otherwise Unclassified Properties

Base Metal Price, % relative 3.9
100
Density, g/cm3 7.8
8.1
Embodied Carbon, kg CO2/kg material 1.9
6.2
Embodied Energy, MJ/kg 26
84
Embodied Water, L/kg 55
440

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 120
31
Resilience: Unit (Modulus of Resilience), kJ/m3 4120
160
Stiffness to Weight: Axial, points 13
15
Stiffness to Weight: Bending, points 25
24
Strength to Weight: Axial, points 84
19
Strength to Weight: Bending, points 51
19
Thermal Diffusivity, mm2/s 10
2.2
Thermal Shock Resistance, points 70
14

Alloy Composition

Carbon (C), % 0.38 to 0.43
0.050 to 0.25
Chromium (Cr), % 0.7 to 1.0
27 to 30
Cobalt (Co), % 0
48 to 52
Iron (Fe), % 93.3 to 94.8
9.7 to 24.5
Manganese (Mn), % 0.65 to 0.9
0 to 1.5
Molybdenum (Mo), % 0.35 to 0.45
0 to 0.5
Nickel (Ni), % 1.7 to 2.0
0 to 4.0
Niobium (Nb), % 0
0 to 0.5
Phosphorus (P), % 0 to 0.012
0 to 0.040
Silicon (Si), % 1.5 to 1.8
0.5 to 1.5
Sulfur (S), % 0 to 0.012
0 to 0.030
Vanadium (V), % 0.050 to 0.1
0