T5 Steel Tool
T5 is a tungsten-based high-speed tool steel, classified under ASTM A600, with 18% tungsten and 9.5% cobalt. Its unique cobalt-tungsten combination provides better cutting efficiency and durability than molybdenum-based tool steels. It offers superior high-temperature performance, toughness, and wear resistance compared to T4. T5 achieves a surface hardness of 68-70 HRC after quenching and is primarily used for cutting tools and turning tools in high-strength alloy carbon steels.
T5 Tool Steel Applications
Cutting Tools
T5 tool steel is commonly used in various cutting tools, such as drills, milling cutters, thread-cutting tools, and knurling tools.
Heavy-Duty Cutting
T5 is ideal for heavy-duty cutting applications, particularly for rough machining of high-strength steels, high-temperature alloys, and titanium alloys. It is also well-suited for processing difficult-to-machine materials, including cast alloys and gray cast iron.
Broaches and Punches
T5 tool steel is widely used in the production of broaches and cold extrusion punches. These tools benefit from T5’s high toughness and wear resistance, making them reliable for precision cutting, shaping, and forming operations.
T5 Tool Steel Heat Treatment
Forging
Heat it slowly to 650-750°C (1190-1380°F) at a rate of no more than 220°C per hour. Once it is at this temperature, heat it more quickly to the forging range of 1000-1150°C (1830-2100°F).
If the temperature drops below 950°C (1742°F), you’ll need to reheat it. After forging, cool the steel slowly in the furnace.
Annealing
Heat the steel to 820-870°C (1508-1598°F) at no more than 220°C per hour. Then, allow it to cool slowly in the furnace at a rate of 10-20°C per hour (50-68°F per hour) down to about 550°C (1022°F), before letting it cool in still air.
After annealing, its hardness should not exceed 285 Brinell.
Stress Relief
After machining and before hardening, stress relieving is important to avoid distortion. Heat the steel in a neutral atmosphere to 600-650°C (1112-1202°F), soak it for about two hours, and then cool it slowly in the furnace.
Hardening
Start by preheating T5 steel slowly to 820-870°C (1508-1598°F). Then, heat it to the austenitizing temperature. If using a salt bath, heat to 1277°C (2331°F); for a controlled atmosphere furnace, heat to 1288°C (2350°F). Quench the steel in a salt bath, thermal quenching, or a warm bath around 550°C (1022°F).
Tempering
Tempering should be done right after quenching. Heat the steel slowly and uniformly to 550-590°C (1022-1094°F). Soak it at the tempering temperature to achieve the desired hardness.
This table illustrates the variation in hardness (HRC) of T5 tool steel at different tempering temperatures.
| Condition | 100°C | 150°C | 200°C | 250°C | 300°C | 350°C | 400°C | 450°C | 500°C | 550°C | 600°C | 650°C |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Temper (°F) | 212 | 302 | 392 | 482 | 572 | 662 | 752 | 842 | 932 | 1022 | 1112 | 1202 |
| Hardness (HRC) | 64 | 64.5 | 63 | 62.5 | 62 | 62 | 62.5 | 63.6 | 64.8 | 66 | 64 | 60 |
| Standard | Equivalent Grade |
|---|---|
| GB 9943 | W18Cr4V2Co8 |
| JIS G 4403 | SKH4A |
| ASTM A600 | T5 |
| ISO | HS18-0-1-10 |
| DIN EN/DIN | S18-1-2-10 |
| W-Nr. | 1.3265 |
| BS EN/BS | BT5 |
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.75 – 0.85 |
| Chromium (Cr) | 3.75 – 5.0 |
| Cobalt (Co) | 7.0 – 9.5 |
| Iron (Fe) | 61.1 – 68.3 |
| Manganese (Mn) | 0.20 – 0.40 |
| Molybdenum (Mo) | 0.50 – 1.25 |
| Phosphorus (P) | ≤ 0.030 |
| Silicon (Si) | 0.20 – 0.40 |
| Sulfur (S) | ≤ 0.030 |
| Tungsten (W) | 17.5 – 19 |
| Vanadium (V) | 1.8 – 2.4 |
| Property | Metric Value | Imperial Value |
|---|---|---|
| Density | 8.75 g/cc | 0.316 lb/in³ |
| Melting Point | 2750 °C | 4982 °F |
| Thermal Conductivity | 30 W/m·K | 17.4 BTU·in/hr·ft²·°F |
| Coefficient of Thermal Expansion | 11.2 μm/m·°C | 6.22 µin/in·°F |
| Property | Metric Value | Imperial Value |
|---|---|---|
| Hardness (HRC) | 65 – 69 HRC | 65 – 69 HRC |
| Poisson’s ratio | 0.27 – 0.30 | 0.27 – 0.30 |
| Modulus of Elasticity | 190 – 210 GPa | 27557 – 30458 ksi |
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