T15 Tool Steel
A tungsten high-speed steel with vanadium and cobalt
Typical values for the temper in the title
T15 contains about 12% tungsten, 5% vanadium and 5% cobalt, with about 1.5% carbon. The high vanadium and carbon form a large amount of very hard vanadium carbides, making it one of the most wear-resistant high-speed steels. Cobalt adds red hardness.
It is used for cutting tools working abrasive or hard materials, and for tools that must hold an edge for a long time. The cost: difficult grinding and low toughness.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Hardness | 277 (annealed) | |
| Modulus of elasticity E | 207 GPa | |
| Density ρ | 8.19 g/cm³ | |
| Machinability | 30% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| W tungsten | about 12.0 (nominal) | red hardness |
| V vanadium | about 5.0 (nominal) | very hard carbides |
| Co cobalt | about 5.0 (nominal) | red hardness |
| Cr chromium | about 4.0 (nominal) | |
| C carbon | about 1.50 (nominal) | carbides and hardness |
| Fe iron | balance |
Nominal composition (ASM Handbook). Exact ranges are in ASTM A600.
Heat treatment
High-speed steels are hardened at a very high temperature (typically around 1200 °C, close to melting), and tempered several times (typically 2–3 times at around 540–565 °C). Multiple tempering produces "secondary hardening" and raises hardness.
| Step / condition | Values | Notes |
|---|---|---|
| Annealed | about 277 HB | for machining |
| Hardening | very high temperature | in vacuum or salt |
| Temper | multiple | very high hardness |
Applications
- Cutting tools for abrasive materials
- Demanding lathe tools
- Milling cutters and broaches
- Tools for hard alloys
- Tools needing long edge life
Fabrication
Grinding
Very difficult because of the vanadium carbides. Requires suitable wheels.
Toughness
Low. Not for tools under impact.
Production
A powder (PM) version also exists, with finer, more uniform carbides.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| M2 | — / — | Not recommended | cheaper, tougher, less wear resistant · material page |
| M42 | 3800-4100 / — | Not recommended | high red hardness, less wear resistance · material page |
| CPM 10V | — / — | Poor | a cold-work powder steel, very wear resistant · material page |
Common mistakes
Grinding T15 with an ordinary wheel
Grinding is slow and the edge burns. Use a suitable wheel.
Choosing T15 for a shock-loaded tool
It is brittle. For such a tool, M2.
Tempering only once
Multiple tempering is needed.
Equivalents, standards and supply
| EN | HS12-1-5-5 (1.3202) |
|---|---|
| JIS | SKH10 |
| Standards | ASTM A600 |
| Forms | rod |
| Producers | Crucible · Nachi |
Learn more
Values are typical and for comparison only. Actual hardness depends on hardening temperature, section size and tempering. For design, rely on the standard, the producer data sheet and the mill certificate. Sources: ASTM A681 and A600, ISO 4957, and producer data sheets (Crucible, Niagara, Alro).
Updated: October 31, 2026