AISI T15 Cobalt Super High-Speed Steel
AISI T15 — Co-W-V super HSS (12 % W, 5 % V, 5 % Co), HRC 66–68. Compare with M42 and ASP2060 for the most abrasive substrates.
AISI T15 (UNS T12015) is a Co-W-V high-speed steel (12 % W, 5 % V, 5 % Co) — one of the hardest standard HSS grades with HRC 66–68 achievable. The combination of high W + high V gives extreme abrasive wear resistance. Used for precision form tools and cutting tools on the most abrasive substrates, where T1 / M2 wear life is insufficient.
Standard composition: C 1.50–1.60 %, Cr 3.75–5.00 %, W 11.75–13.00 %, V 4.50–5.25 %, Co 4.75–5.25 %, Mo ≤ 1.00 %, Mn ≤ 0.40 %, Si ≤ 0.50 %, balance Fe
Hardness: Annealed HB 241–277; hardened HRC 65–68
Heat treatment: Austenitise 1,235–1,260 °C, oil or salt quench, double temper 540–565 °C
Properties: The 12 % W + 5 % V + 5 % Co gives exceptional hot hardness and wear resistance. Hardness up to HRC 68. Toughness lower than M2. Used for the most demanding cutting applications.
Applications: High-performance slitter blades, hard-to-machine aerospace alloys, advanced die-casting tooling.
Cross-reference: ≈ JIS SKH10, DIN 1.3202, GB W12Cr4V5Co5, BS BT15.
See also.
