W1 Tool Steel Properties, Composition, Heat Treatment
AISI W1 Tool Steel (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, poor hardenability, low plasticity and strength.
W1 Steel Properties
The following data sheets summarize W1 steel properties such as chemical composition, physical and mechanical properties, etc.
Chemical Composition
| W1 Chemical Composition, % | ||||||||||||
| Standard | AISI (UNS) | C | Si | Mn | P, ≤ | S, ≤ | Cr, ≤ | Mo | V, ≤ | W | Cu | Ni |
| 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 | 1.00-1.10 |
| 10.5 | 1.05-1.15 |
| 11 | 1.10-1.20 |
| 11.5 | 1.15-1.25 |
Physical Properties
W1 metal physical properties such as density, specific heat capacity, and thermal properties, elastic modulus are given in the table below.
| Physical Properties | Metric | Imperial |
| Density | 7.84 g/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 106 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
W1 steel heat treatment such as normalizing, annealing, hardening and tempering are:
Normalizing and Annealing Temperatures
- Normalizing: 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); 0.90-1.10 C, 870 °C (1600 °F); 1.10-1.40 C, 870-925 °C (1600-1700 °F). 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); 0.90-1.40 C, 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. Time held at temperature varies from 1 hour for light sections to 4 hours for heavy sections and large furnace charges of high alloy steel.
- Rate of cooling: ≤ 22 °C/h (40 °F/h)
- Annealed Brinell hardness: 156-201 HB.
Hardening and Tempering
- Rate of heating: Slowly
- Hardening
- Preheat temperature 565-650 °C (1050-1200 °F), recommended for large tools and tools with intricate sections.
- Hardening temperature 760-815 °C (1400-1550 °F)
- Time at temperature: 10-30 minutes.
- Quenching medium: brine or oil
- Tempering temperature: 175-345 °C (350-650 °F)
- Approximate tempered Rockwell C hardness: 50-64 HRC.
Applications of W1 Tool Steel
W1 tool steel is suitable for cold heading, striking, coining and embossing tools; hole punching tools, woodworking tools such as milling cutters, countersinks; hard metal cutting tools such as taps and reamers; wear-resistant machine parts.
AISI W1 Steel Equivalent Material
AISI W1 steel equivalent material is listed in the table below, including European EN, ISO, German DIN, Chinese GB and Japanese JIS standard, etc.
| AISI W1 Steel Equivalent Material | |||||||||||||||||||
| US | European Union | ISO | Germany | Japan | China | Australia | India | Rusia | Korea | ||||||||||
| Standard | Steel (UNS) | Standard | Steel Name (Material Number) | Standard | Designation | Standard | Steel Name (Material Number) | Standard | Steel Grade | Standard | Steel Grade | Standard | Grade | Standard | Grade | Standard | Grade | Standard | Grade |
| AISI, SAE; ASTM A681 | W1-7; W1-8; W1-8.5; W1-9; W1-9.5; W1-10; W1-10.5; W1-11; W1-11.5 (T72301) | EN ISO 4957 | C70U (1.1520); C80U (1.1525); C90U (1.1535); C105 (1.1545); C120U (1.1555) | ISO 4957 | C70U; C80U; C90U; C105; C120U | DIN EN ISO 4957; DIN 17350 | C70U (1.1520); C80U (1.1525); C90U (1.1535); C105 (1.1545); C120U (1.1555); C80W2 (Old Designation) | JIS G4401 | SK70; SK75 (SK6); SK80; SK85 (SK5); SK90; SK95 (SK4); SK105 (SK3); SK120 (SK2) | GB/T 1298 | T7; T8; T8Mn; T9; T10; T11; T12; T13 | ||||||||
