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SAE-AISI H21 (T20821) Tungsten Hot-Work Steel

SAE-AISI H21 steel is a tool steel. H21 is the designation in both the SAE and AISI systems for this material. T20821 is the UNS number.

The properties of SAE-AISI H21 steel include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare SAE-AISI H21 steel to: tool steels (top), all iron alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Elastic (Young's, Tensile) Modulus

200 GPa 29 x 106 psi

Poisson's Ratio


Shear Modulus

76 GPa 11 x 106 psi

Tensile Strength: Ultimate (UTS)

720 to 1790 MPa 100 to 260 x 103 psi

Thermal Properties

Latent Heat of Fusion

250 J/g

Melting Completion (Liquidus)

1630 °C 2960 °F

Melting Onset (Solidus)

1580 °C 2880 °F

Specific Heat Capacity

440 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

27 W/m-K 16 BTU/h-ft-°F

Thermal Expansion

11 µm/m-K

Otherwise Unclassified Properties

Base Metal Price

23 % relative


8.5 g/cm3 530 lb/ft3

Embodied Carbon

4.5 kg CO2/kg material

Embodied Energy

68 MJ/kg 29 x 103 BTU/lb

Embodied Water

72 L/kg 8.6 gal/lb

Common Calculations

PREN (Pitting Resistance)


Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

23 points

Strength to Weight: Axial

23 to 58 points

Strength to Weight: Bending

21 to 38 points

Thermal Diffusivity

7.1 mm2/s

Thermal Shock Resistance

24 to 59 points

Alloy Composition

Iron (Fe)Fe 87.6 to 93.8
Tungsten (W)W 8.5 to 10
Chromium (Cr)Cr 3.0 to 3.8
Vanadium (V)V 0.3 to 0.6
Silicon (Si)Si 0.15 to 0.5
Carbon (C)C 0.28 to 0.36
Manganese (Mn)Mn 0.15 to 0.4
Nickel (Ni)Ni 0 to 0.3
Copper (Cu)Cu 0 to 0.25
Phosphorus (P)P 0 to 0.030
Sulfur (S)S 0 to 0.030

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

SAE J437: Selection and Heat Treatment of Tool and Die Steels

ASTM A681: Standard Specification for Tool Steels Alloy

Tool Steels, 5th ed., George Roberts et al., 1998

Tool Steels: Properties and Performance, Rafael A. Mesquita (editor), 2016

ASM Specialty Handbook: Carbon and Alloy Steels, J. R. Davis (editor), 1996