SAE-AISI O2 Steel vs. S21800 Stainless Steel

Both SAE-AISI O2 steel and S21800 stainless steel are iron alloys. They have 65% of their average alloy composition in common. There are 19 material properties with values for both materials. Properties with values for just one material (16, in this case) are not shown.

For each property being compared, the top bar is SAE-AISI O2 steel and the bottom bar is S21800 stainless steel.

SAE-AISI O2 (T31502) Oil-Hardening Steel UNS S21800 (Alloy 218) Stainless Steel

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa		190
Elastic (Young's, Tensile) Modulus, GPa		190

Poisson's Ratio		0.29
Poisson's Ratio		0.28

Shear Modulus, GPa		72
Shear Modulus, GPa		75

Tensile Strength: Ultimate (UTS), MPa		640 to 2050
Tensile Strength: Ultimate (UTS), MPa		740

Thermal Properties

Latent Heat of Fusion, J/g		250
Latent Heat of Fusion, J/g		340

Melting Completion (Liquidus), °C		1450
Melting Completion (Liquidus), °C		1360

Melting Onset (Solidus), °C		1410
Melting Onset (Solidus), °C		1310

Specific Heat Capacity, J/kg-K		470
Specific Heat Capacity, J/kg-K		500

Thermal Expansion, µm/m-K		11
Thermal Expansion, µm/m-K		16

Otherwise Unclassified Properties

Base Metal Price, % relative		2.4
Base Metal Price, % relative		15

Density, g/cm³		7.8
Density, g/cm³		7.5

Embodied Carbon, kg CO₂/kg material		1.8
Embodied Carbon, kg CO₂/kg material		3.1

Embodied Energy, MJ/kg		26
Embodied Energy, MJ/kg		45

Embodied Water, L/kg		50
Embodied Water, L/kg		150

Common Calculations

Stiffness to Weight: Axial, points		13
Stiffness to Weight: Axial, points		14

Stiffness to Weight: Bending, points		24
Stiffness to Weight: Bending, points		26

Strength to Weight: Axial, points		23 to 73
Strength to Weight: Axial, points		27

Strength to Weight: Bending, points		21 to 46
Strength to Weight: Bending, points		24

Thermal Shock Resistance, points		22 to 70
Thermal Shock Resistance, points		17

Alloy Composition

Carbon (C), %		0.85 to 1.0
Carbon (C), %		0 to 0.1

Chromium (Cr), %		0 to 0.5
Chromium (Cr), %		16 to 18

Copper (Cu), %		0 to 0.25
Copper (Cu), %		0

Iron (Fe), %		95 to 97.8
Iron (Fe), %		59.1 to 65.4

Manganese (Mn), %		1.4 to 1.8
Manganese (Mn), %		7.0 to 9.0

Molybdenum (Mo), %		0 to 0.3
Molybdenum (Mo), %		0

Nickel (Ni), %		0 to 0.3
Nickel (Ni), %		8.0 to 9.0

Nitrogen (N), %		0
Nitrogen (N), %		0.080 to 0.18

Phosphorus (P), %		0 to 0.030
Phosphorus (P), %		0 to 0.060

Silicon (Si), %		0 to 0.5
Silicon (Si), %		3.5 to 4.5

Sulfur (S), %		0 to 0.030
Sulfur (S), %		0 to 0.030

Vanadium (V), %		0 to 0.3
Vanadium (V), %		0