AISI M1 Molybdenum High-Speed Steel
AISI M1 (UNS T11301) — tungsten-free Mo HSS, HRC 63–65. Compare with M2, M3, M35 for slitter blades and drills where M2 is overkill.
AISI M1 (UNS T11301) is a tungsten-free Mo-based high-speed steel (8.5 % Mo) — historically significant as the first commercial Mo-HSS. Hardened to HRC 63–65, it is the entry-grade HSS for slitter blades, drills and taps where M2 wear life is overkill but M50 corrosion resistance is unnecessary.
Standard composition: C 0.78–0.84 %, Cr 3.50–4.00 %, Mo 8.20–9.20 %, W 1.40–2.10 %, V 1.00–1.30 %, V 1.00–1.30 %, Mn ≤ 0.40 %, Si ≤ 0.50 %, balance Fe
Hardness: Annealed HB 217–248; hardened HRC 62–65
Heat treatment: Austenitise 1,180–1,200 °C, oil or salt quench, double temper 540–560 °C
Properties: Tungsten-lean M-series HSS, similar to M2 but with higher Mo. Better toughness than M2 at the cost of some hot hardness. Used historically for cutting tools, less common today.
Applications: Slitter blades for thin film, drills, taps, reamers, broaches.
Cross-reference: ≈ DIN 1.3346 (close).
See also.
