S21800 Stainless Steel vs. SAE-AISI P20 Steel

Both S21800 stainless steel and SAE-AISI P20 steel are iron alloys. They have 65% of their average alloy composition in common. There are 20 material properties with values for both materials. Properties with values for just one material (15, in this case) are not shown.

For each property being compared, the top bar is S21800 stainless steel and the bottom bar is SAE-AISI P20 steel.

UNS S21800 (Alloy 218) Stainless Steel SAE-AISI P20 (T51620) Low-Carbon Mould Steel

Metric UnitsUS Customary Units

Mechanical Properties

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

Poisson's Ratio		0.28
Poisson's Ratio		0.29

Shear Modulus, GPa		75
Shear Modulus, GPa		73

Tensile Strength: Ultimate (UTS), MPa		740
Tensile Strength: Ultimate (UTS), MPa		540 to 1050

Thermal Properties

Latent Heat of Fusion, J/g		340
Latent Heat of Fusion, J/g		260

Melting Completion (Liquidus), °C		1360
Melting Completion (Liquidus), °C		1460

Melting Onset (Solidus), °C		1310
Melting Onset (Solidus), °C		1420

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

Thermal Expansion, µm/m-K		16
Thermal Expansion, µm/m-K		12

Otherwise Unclassified Properties

Base Metal Price, % relative		15
Base Metal Price, % relative		2.8

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

Embodied Carbon, kg CO₂/kg material		3.1
Embodied Carbon, kg CO₂/kg material		1.6

Embodied Energy, MJ/kg		45
Embodied Energy, MJ/kg		21

Embodied Water, L/kg		150
Embodied Water, L/kg		52

Common Calculations

PREN (Pitting Resistance)		19
PREN (Pitting Resistance)		2.6

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

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

Strength to Weight: Axial, points		27
Strength to Weight: Axial, points		19 to 37

Strength to Weight: Bending, points		24
Strength to Weight: Bending, points		19 to 29

Thermal Shock Resistance, points		17
Thermal Shock Resistance, points		18 to 35

Alloy Composition

Carbon (C), %		0 to 0.1
Carbon (C), %		0.28 to 0.4

Chromium (Cr), %		16 to 18
Chromium (Cr), %		0.4 to 2.0

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

Iron (Fe), %		59.1 to 65.4
Iron (Fe), %		95.2 to 98.5

Manganese (Mn), %		7.0 to 9.0
Manganese (Mn), %		0.35 to 0.71

Molybdenum (Mo), %		0
Molybdenum (Mo), %		0.3 to 0.55

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

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

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

Silicon (Si), %		3.5 to 4.5
Silicon (Si), %		0.2 to 0.8

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