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AISI W1 (T72301) Water-Hardening Steel

AISI W1 steel is a tool steel. W1 is the AISI designation for this material. T72301 is the UNS number. It has the highest thermal conductivity among the tool steels in the database.

The properties of AISI W1 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 AISI W1 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

190 GPa 27 x 106 psi

Poisson's Ratio


Shear Modulus

72 GPa 10 x 106 psi

Tensile Strength: Ultimate (UTS)

590 to 2320 MPa 86 to 340 x 103 psi

Thermal Properties

Latent Heat of Fusion

250 J/g

Melting Completion (Liquidus)

1450 °C 2640 °F

Melting Onset (Solidus)

1410 °C 2570 °F

Specific Heat Capacity

470 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

48 W/m-K 28 BTU/h-ft-°F

Thermal Expansion

10 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

7.1 % IACS

Electrical Conductivity: Equal Weight (Specific)

8.2 % IACS

Otherwise Unclassified Properties

Base Metal Price

2.2 % relative


7.8 g/cm3 490 lb/ft3

Embodied Carbon

1.6 kg CO2/kg material

Embodied Energy

21 MJ/kg 9.2 x 103 BTU/lb

Embodied Water

47 L/kg 5.5 gal/lb

Common Calculations

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

21 to 83 points

Strength to Weight: Bending

20 to 50 points

Thermal Diffusivity

13 mm2/s

Thermal Shock Resistance

22 to 85 points

Alloy Composition

Iron (Fe)Fe 96.4 to 98.9
Carbon (C)C 0.7 to 1.5
Manganese (Mn)Mn 0.35 to 0.73
Silicon (Si)Si 0.1 to 0.4
Nickel (Ni)Ni 0 to 0.2
Copper (Cu)Cu 0 to 0.2
Chromium (Cr)Cr 0 to 0.15
Tungsten (W)W 0 to 0.15
Molybdenum (Mo)Mo 0 to 0.1
Vanadium (V)V 0 to 0.1
Phosphorus (P)P 0 to 0.025
Sulfur (S)S 0 to 0.025

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

Followup Questions

Similar Alloys

Further Reading

ASTM A686: Standard Specification for Tool Steel, Carbon

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

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