ASTM A387 Grade 21 Steel vs. R05240 Alloy

ASTM A387 grade 21 steel belongs to the iron alloys classification, while R05240 alloy belongs to the otherwise unclassified metals. There are 18 material properties with values for both materials. Properties with values for just one material (14, 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 R05240 alloy.

ASTM A387 Grade 21 (K31545) 3Cr-1Mo Steel UNS R05240 Tantalum-Niobium Alloy

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa		190
Elastic (Young's, Tensile) Modulus, GPa		150

Elongation at Break, %		21
Elongation at Break, %		25

Poisson's Ratio		0.29
Poisson's Ratio		0.36

Shear Modulus, GPa		74
Shear Modulus, GPa		57

Tensile Strength: Ultimate (UTS), MPa		500 to 590
Tensile Strength: Ultimate (UTS), MPa		270

Tensile Strength: Yield (Proof), MPa		230 to 350
Tensile Strength: Yield (Proof), MPa		170

Thermal Properties

Latent Heat of Fusion, J/g		260
Latent Heat of Fusion, J/g		210

Specific Heat Capacity, J/kg-K		470
Specific Heat Capacity, J/kg-K		190

Thermal Expansion, µm/m-K		13
Thermal Expansion, µm/m-K		6.8

Otherwise Unclassified Properties

Density, g/cm³		7.9
Density, g/cm³		14

Embodied Water, L/kg		62
Embodied Water, L/kg		460

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m³		84 to 110
Resilience: Ultimate (Unit Rupture Work), MJ/m³		59

Resilience: Unit (Modulus of Resilience), kJ/m³		140 to 320
Resilience: Unit (Modulus of Resilience), kJ/m³		90

Stiffness to Weight: Axial, points		13
Stiffness to Weight: Axial, points		6.3

Stiffness to Weight: Bending, points		24
Stiffness to Weight: Bending, points		13

Strength to Weight: Axial, points		18 to 21
Strength to Weight: Axial, points		5.4

Strength to Weight: Bending, points		18 to 20
Strength to Weight: Bending, points		6.8

Thermal Shock Resistance, points		14 to 17
Thermal Shock Resistance, points		18

Alloy Composition

Carbon (C), %		0.050 to 0.15
Carbon (C), %		0 to 0.010

Chromium (Cr), %		2.8 to 3.3
Chromium (Cr), %		0

Hydrogen (H), %		0
Hydrogen (H), %		0 to 0.0015

Iron (Fe), %		94.4 to 96
Iron (Fe), %		0 to 0.010

Manganese (Mn), %		0.3 to 0.6
Manganese (Mn), %		0

Molybdenum (Mo), %		0.9 to 1.1
Molybdenum (Mo), %		0 to 0.020

Nickel (Ni), %		0
Nickel (Ni), %		0 to 0.010

Niobium (Nb), %		0
Niobium (Nb), %		35 to 42

Nitrogen (N), %		0
Nitrogen (N), %		0 to 0.010

Oxygen (O), %		0
Oxygen (O), %		0 to 0.020

Phosphorus (P), %		0 to 0.025
Phosphorus (P), %		0

Silicon (Si), %		0 to 0.5
Silicon (Si), %		0 to 0.0050

Sulfur (S), %		0 to 0.025
Sulfur (S), %		0

Tantalum (Ta), %		0
Tantalum (Ta), %		57.9 to 65

Titanium (Ti), %		0
Titanium (Ti), %		0 to 0.010

Tungsten (W), %		0
Tungsten (W), %		0 to 0.050