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ACI-ASTM CF8M Steel vs. S81921 Stainless Steel

Both ACI-ASTM CF8M steel and S81921 stainless steel are iron alloys. They have a moderately high 91% of their average alloy composition in common. There are 32 material properties with values for both materials. Properties with values for just one material (2, in this case) are not shown.

For each property being compared, the top bar is ACI-ASTM CF8M steel and the bottom bar is S81921 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 170
260
Elastic (Young's, Tensile) Modulus, GPa 200
200
Elongation at Break, % 50
29
Fatigue Strength, MPa 280
370
Poisson's Ratio 0.28
0.28
Shear Modulus, GPa 78
79
Tensile Strength: Ultimate (UTS), MPa 540
710
Tensile Strength: Yield (Proof), MPa 290
500

Thermal Properties

Latent Heat of Fusion, J/g 300
290
Maximum Temperature: Corrosion, °C 420
430
Maximum Temperature: Mechanical, °C 1000
990
Melting Completion (Liquidus), °C 1440
1430
Melting Onset (Solidus), °C 1400
1390
Specific Heat Capacity, J/kg-K 480
480
Thermal Conductivity, W/m-K 16
15
Thermal Expansion, µm/m-K 16
13

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 2.0
2.2
Electrical Conductivity: Equal Weight (Specific), % IACS 2.3
2.5

Otherwise Unclassified Properties

Base Metal Price, % relative 19
14
Density, g/cm3 7.8
7.7
Embodied Carbon, kg CO2/kg material 3.8
2.9
Embodied Energy, MJ/kg 53
41
Embodied Water, L/kg 160
150

Common Calculations

PREN (Pitting Resistance) 28
28
Resilience: Ultimate (Unit Rupture Work), MJ/m3 230
180
Resilience: Unit (Modulus of Resilience), kJ/m3 210
630
Stiffness to Weight: Axial, points 14
14
Stiffness to Weight: Bending, points 25
25
Strength to Weight: Axial, points 19
25
Strength to Weight: Bending, points 19
23
Thermal Diffusivity, mm2/s 4.3
4.0
Thermal Shock Resistance, points 12
20

Alloy Composition

Carbon (C), % 0 to 0.080
0 to 0.030
Chromium (Cr), % 18 to 21
19 to 22
Iron (Fe), % 60.3 to 71
66.7 to 75.9
Manganese (Mn), % 0 to 1.5
2.0 to 4.0
Molybdenum (Mo), % 2.0 to 3.0
1.0 to 2.0
Nickel (Ni), % 9.0 to 12
2.0 to 4.0
Nitrogen (N), % 0
0.14 to 0.2
Phosphorus (P), % 0 to 0.040
0 to 0.040
Silicon (Si), % 0 to 2.0
0 to 1.0
Sulfur (S), % 0 to 0.040
0 to 0.030