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ASTM A369 Grade FP21 vs. SAE-AISI 8720 Steel

Both ASTM A369 grade FP21 and SAE-AISI 8720 steel are iron alloys. Both are furnished in the annealed condition. They have a very high 97% of their average alloy composition in common. There are 31 material properties with values for both materials. Properties with values for just one material (1, in this case) are not shown.

For each property being compared, the top bar is ASTM A369 grade FP21 and the bottom bar is SAE-AISI 8720 steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 140
150
Elastic (Young's, Tensile) Modulus, GPa 190
190
Elongation at Break, % 20
25
Fatigue Strength, MPa 160
240
Poisson's Ratio 0.29
0.29
Shear Modulus, GPa 74
73
Shear Strength, MPa 300
320
Tensile Strength: Ultimate (UTS), MPa 470
500
Tensile Strength: Yield (Proof), MPa 240
330

Thermal Properties

Latent Heat of Fusion, J/g 260
250
Maximum Temperature: Mechanical, °C 470
410
Melting Completion (Liquidus), °C 1470
1460
Melting Onset (Solidus), °C 1430
1420
Specific Heat Capacity, J/kg-K 470
470
Thermal Conductivity, W/m-K 41
39
Thermal Expansion, µm/m-K 13
11

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 7.7
7.3
Electrical Conductivity: Equal Weight (Specific), % IACS 8.8
8.3

Otherwise Unclassified Properties

Base Metal Price, % relative 4.0
2.6
Density, g/cm3 7.8
7.8
Embodied Carbon, kg CO2/kg material 1.8
1.5
Embodied Energy, MJ/kg 23
20
Embodied Water, L/kg 61
50

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 80
110
Resilience: Unit (Modulus of Resilience), kJ/m3 150
290
Stiffness to Weight: Axial, points 13
13
Stiffness to Weight: Bending, points 24
24
Strength to Weight: Axial, points 17
18
Strength to Weight: Bending, points 17
18
Thermal Diffusivity, mm2/s 11
10
Thermal Shock Resistance, points 14
17

Alloy Composition

Carbon (C), % 0.050 to 0.15
0.18 to 0.23
Chromium (Cr), % 2.7 to 3.4
0.4 to 0.6
Iron (Fe), % 94.3 to 96.2
96.8 to 98
Manganese (Mn), % 0.3 to 0.6
0.7 to 0.9
Molybdenum (Mo), % 0.8 to 1.1
0.2 to 0.3
Nickel (Ni), % 0
0.4 to 0.7
Phosphorus (P), % 0 to 0.025
0 to 0.035
Silicon (Si), % 0 to 0.5
0.15 to 0.35
Sulfur (S), % 0 to 0.025
0 to 0.040