AISI T1 Tungsten High-Speed Steel
AISI T1 (UNS T12001) — original 18 % W tungsten grade, HRC 63–65. Compare with M2 and T15 for legacy tooling designs.
AISI T1 (UNS T12001) is the original tungsten high-speed steel (18 % W) — the historical baseline of the HSS family, gradually displaced by Mo-bearing M-series grades but still specified for legacy tool designs. Hardened to HRC 63–65.
Standard composition: C 0.65–0.80 %, Cr 3.75–4.50 %, W 17.25–18.75 %, V 0.90–1.30 %, Mo ≤ 0.10 %, Co ≤ 0.10 %, Mn ≤ 0.40 %, Si ≤ 0.50 %, balance Fe
Hardness: Annealed HB 217–248; hardened HRC 62–65
Heat treatment: Austenitise 1,260–1,280 °C, oil or salt quench, double temper 540–565 °C
Properties: Classic tungsten HSS. Excellent hot hardness from the 18 % W. Lower Mo than M-series, which makes it tougher. Now largely replaced by M-series for cost reasons, but still used in some hot-work applications.
Applications: Legacy cutting tools, high-temperature slitter blades (pre-M42 era), die-casting punches.
Cross-reference: ≈ JIS SKH2, DIN 1.3355, GB W18Cr4V, BS BT1.
See also.
