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ASTM A387 Grade 91 Class 2 vs. SAE-AISI 8645 Steel

Both ASTM A387 grade 91 class 2 and SAE-AISI 8645 steel are iron alloys. They have a moderately high 91% 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 A387 grade 91 class 2 and the bottom bar is SAE-AISI 8645 steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 200
180 to 200
Elastic (Young's, Tensile) Modulus, GPa 190
190
Elongation at Break, % 20
12 to 23
Fatigue Strength, MPa 330
280 to 350
Poisson's Ratio 0.28
0.29
Shear Modulus, GPa 75
73
Shear Strength, MPa 420
380 to 400
Tensile Strength: Ultimate (UTS), MPa 670
600 to 670
Tensile Strength: Yield (Proof), MPa 470
390 to 560

Thermal Properties

Latent Heat of Fusion, J/g 270
250
Maximum Temperature: Mechanical, °C 600
410
Melting Completion (Liquidus), °C 1460
1460
Melting Onset (Solidus), °C 1420
1420
Specific Heat Capacity, J/kg-K 470
470
Thermal Conductivity, W/m-K 26
39
Thermal Expansion, µm/m-K 13
13

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 8.9
7.3
Electrical Conductivity: Equal Weight (Specific), % IACS 10
8.4

Otherwise Unclassified Properties

Base Metal Price, % relative 7.0
2.6
Density, g/cm3 7.8
7.8
Embodied Carbon, kg CO2/kg material 2.6
1.5
Embodied Energy, MJ/kg 37
20
Embodied Water, L/kg 88
50

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 120
77 to 120
Resilience: Unit (Modulus of Resilience), kJ/m3 580
420 to 840
Stiffness to Weight: Axial, points 14
13
Stiffness to Weight: Bending, points 25
24
Strength to Weight: Axial, points 24
21 to 24
Strength to Weight: Bending, points 22
20 to 22
Thermal Diffusivity, mm2/s 6.9
10
Thermal Shock Resistance, points 19
18 to 20

Alloy Composition

Aluminum (Al), % 0 to 0.020
0
Carbon (C), % 0.080 to 0.12
0.43 to 0.48
Chromium (Cr), % 8.0 to 9.5
0.4 to 0.6
Iron (Fe), % 87.3 to 90.3
96.5 to 97.7
Manganese (Mn), % 0.3 to 0.6
0.75 to 1.0
Molybdenum (Mo), % 0.85 to 1.1
0.15 to 0.25
Nickel (Ni), % 0 to 0.4
0.4 to 0.7
Niobium (Nb), % 0.060 to 0.1
0
Nitrogen (N), % 0.030 to 0.070
0
Phosphorus (P), % 0 to 0.020
0 to 0.035
Silicon (Si), % 0.2 to 0.5
0.15 to 0.35
Sulfur (S), % 0 to 0.010
0 to 0.040
Titanium (Ti), % 0 to 0.010
0
Vanadium (V), % 0.18 to 0.25
0
Zirconium (Zr), % 0 to 0.010
0