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ASTM A387 Grade 21 Steel vs. SAE-AISI 81B45 Steel

Both ASTM A387 grade 21 steel and SAE-AISI 81B45 steel are iron alloys. 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 A387 grade 21 steel and the bottom bar is SAE-AISI 81B45 steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 150 to 180
160 to 200
Elastic (Young's, Tensile) Modulus, GPa 190
190
Elongation at Break, % 21
12 to 24
Fatigue Strength, MPa 160 to 250
250 to 350
Poisson's Ratio 0.29
0.29
Shear Modulus, GPa 74
73
Shear Strength, MPa 310 to 370
340 to 400
Tensile Strength: Ultimate (UTS), MPa 500 to 590
540 to 670
Tensile Strength: Yield (Proof), MPa 230 to 350
350 to 560

Thermal Properties

Latent Heat of Fusion, J/g 260
250
Maximum Temperature: Mechanical, °C 480
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
40
Thermal Expansion, µm/m-K 13
12

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 7.6
7.2
Electrical Conductivity: Equal Weight (Specific), % IACS 8.8
8.3

Otherwise Unclassified Properties

Base Metal Price, % relative 4.1
2.3
Density, g/cm3 7.9
7.8
Embodied Carbon, kg CO2/kg material 1.8
1.5
Embodied Energy, MJ/kg 23
20
Embodied Water, L/kg 62
49

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 84 to 110
77 to 110
Resilience: Unit (Modulus of Resilience), kJ/m3 140 to 320
320 to 840
Stiffness to Weight: Axial, points 13
13
Stiffness to Weight: Bending, points 24
24
Strength to Weight: Axial, points 18 to 21
19 to 24
Strength to Weight: Bending, points 18 to 20
19 to 22
Thermal Diffusivity, mm2/s 11
11
Thermal Shock Resistance, points 14 to 17
17 to 21

Alloy Composition

Boron (B), % 0
0.00050 to 0.0030
Carbon (C), % 0.050 to 0.15
0.43 to 0.48
Chromium (Cr), % 2.8 to 3.3
0.35 to 0.55
Iron (Fe), % 94.4 to 96
97 to 98
Manganese (Mn), % 0.3 to 0.6
0.75 to 1.0
Molybdenum (Mo), % 0.9 to 1.1
0.080 to 0.15
Nickel (Ni), % 0
0.2 to 0.4
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

Comparable Variants