Properties, composition, heat treatment of W1 tool steel

February 6, 2024 Luciano Bertene

Tool steel AISI W1 (UNS T72301)

AISI W1 steel is a water-hardening tool steel, which has high hardness and wear resistance after quenching and tempering, but low hot hardness, low hardenability, low plasticity and strength.

W1 steel properties

The following data sheets summarize the properties of W1 steel such as chemical composition, physical and mechanical properties, etc.

Chemical composition

Chemical Composition W1,%
Standard	AISI (UNS)	W	Yes	Mn	P, ≤	S, ≤	Cr, ≤	Mo	V, ≤	W	Ass	No
ASTM A686	W1 (T72301)	0.70-1.50	0.10-0.40	0.10-0.40	0.030	0.030	0.15	0.10	0.10	0.15	0.20	0.20

Note: Specified carbon ranges are designated by suffix numbers.

Suffix	Carbon range, %
8	0.80-0.90
8.5	0.85-0.95
9	0.90-1.00
9.5	0.95-1.05
10	1h00-1h10
10.5	1.05-1.15
11	1.10-1.20
11.5	1.15-1.25

Physical properties

The physical properties of W1 metal such as density, specific heat capacity and thermal properties, modulus of elasticity are given in the table below.

Physical properties	Metric	Imperial
Density	7.84g/cm3	0.282 lb/in3
Specific heat capacity	460 J/kg·K	0.11 Btu/lb°F
Elastic modulus (Modulus of elasticity)	205 GPa	29.7 x 10 ⁶ psi
Thermal conductivity	48.3 W/m·K (95 °C)	27.9 Btu/ft·h·°F (200°F)
	33.0 W/m·K (260 °C)	24.0 Btu/ft·h·°F (500°F)
	38.1 W/m·K (400 °C)	22.0 Btu/ft·h·°F (750°F)
	34.6 W/m·K (540 °C)	20.0 Btu/ft·h·°F (1000°F)
	29.4 W/m·K (675 °C)	17.0 Btu/ft·h·°F (1250°F)
	24.2 W/m·K (815°C)	14.0 Btu/ft·h·°F (1500°F)
Coefficient of thermal expansion (CTE)	10.4 μm/m·K (20-100 °C)	5.76 μin./in.°F (70-200 °F)
	11.0 μm/m·K (20-200 °C)	6.13 μin./in.°F (70-400 °F)
	13.1 μm/m·K (20-425 °C)	7.28 μin./in.°F (70-800 °F)
	13.8 μm/m·K (20-500 °C)	7.64 μin./in.°F (70-930 °F)
	14.2 μm/m·K (20-600 °C)	7.90 μin./in.°F (70-1110 °F)

W1 Steel Heat Treatment

The heat treatment of W1 steel such as normalizing, annealing, hardening and tempering are:

Normalizing and annealing temperatures

Normalization: 790-925 °C (1450-1700 °F), temperature varies with carbon content: 0.60-0.75 C, 815 °C (1500 °F); 0.75-0.90°C, 790°C (1450°F); 0.90-1.10C, 870°C (1600°F); 1.10-1.40 C, 870-925 °C (1600-1700 °F). The time held at temperature varies from 15 minutes for small sections to 1 hour for large sections. Cooling is carried out in still air. Normalizing should not be confused with low temperature annealing.
Annealing: 740-790°C (1360-1450°F), temperature varies with carbon content: 0.60-0.90°C, 740-790°C (1360-1450°F); 0.90-1.40C, 760-790°C (1400-1450°F). The upper limit of the range should be used for large sections and the lower limit for smaller sections. The time held at temperature varies from 1 hour for light sections to 4 hours for heavy sections and large high-alloy steel furnace charges.
Cooling rate: ≤ 22°C/h (40°F/h)
Annealed Brinell hardness: 156-201 HB.

Hardening and Tempering

Heating Rate: Slowly
Hardening
- Preheat temperature 565-650°C (1050-1200°F), recommended for large tools and tools with complex sections.
- Hardening temperature 760-815°C (1400-1550°F)
Time to temperature: 10-30 minutes.
Quenching medium: brine or oil
Quenching Temperature: 175-345°C (350-650°F)
Approximate tempered Rockwell C hardness: 50-64 HRC.

W1 tool steel applications

W1 tool steel is suitable for cold heading, striking, coining and engraving tools; drilling tools, woodworking tools such as milling cutters, countersinks; carbide cutting tools such as taps and reamers; wear-resistant machine parts.

Equivalent material in AISI W1 steel

The material equivalent to AISI W1 steel is listed in the table below, including European EN, ISO, German DIN, Chinese GB and Japanese JIS standards, etc.

Equivalent material in AISI W1 steel

USA

European Union

ISO

Germany

Japan

China

Australia

India

Russia

Korea

Standard