M2 Tool Steel – Frequently Asked Questions
M2 is the world’s most widely used high speed steel (HSS). It offers an excellent balance of red hardness, wear resistance, toughness, and grindability, and is the standard reference grade for all other HSS grades.
M2 contains 0.78–0.88% Carbon, 3.75–4.50% Chromium, 4.50–5.50% Molybdenum, 5.50–6.75% Tungsten, 1.75–2.20% Vanadium, and 0.15–0.40% Silicon.
Molybdenum and tungsten provide red hardness by forming stable carbides that resist softening at high temperatures. Vanadium creates very hard carbides that improve abrasion resistance and edge retention. Chromium improves hardenability and oxidation resistance.
M2 (AISI/SAE) = 1.3343 / HS6-5-2 (DIN/EN) = SKH51 (JIS) = BM2 (BS) = R6M5 (GOST). These are compositionally very close and generally interchangeable for most applications.
Annealed hardness is 207–255 HB. After hardening and tempering it reaches 62–65 HRC with tensile strength of approximately 2400–2700 MPa. Density is 8.16 g/cm³. M2 retains useful hardness up to around 600°C.
Yes, M2 handles interrupted cuts well in standard cutting applications like drills, taps, and milling cutters. For very heavy shock loading, tougher grades like M7 or cobalt HSS grades (M35, M42) may be more appropriate.
M2 outperforms cold-work steels in high-speed cutting because its carbides remain stable at elevated temperatures. For cold-work abrasion at room temperature, D2 will outlast M2 as it has a greater volume of wear-resistant carbides.
M2 is austenitized at 1190–1230°C (2175–2250°F). This high temperature is needed to dissolve the stable alloy carbides into the austenite. Use a vacuum or salt bath furnace to prevent decarburization. Soak time at temperature should be kept short — typically 2–5 minutes.
Preheat in two stages: first to 450–500°C, then equalise at 850–900°C before raising to the hardening temperature. Skipping preheat on M2 causes thermal shock cracking due to its high austenitizing temperature.
M2 is used for twist drills, end mills, milling cutters, reamers, taps, broaches, gear cutters, saw blades, cold-forming punches, threading dies, and injection mold components. It is the default HSS grade when no specific grade is stated.
M2 replaced T1 (tungsten HSS) as the industry standard because molybdenum is cheaper than tungsten and M2 provides equivalent or better performance in most cutting tool applications with an ideal balance of cost, performance, and grindability.
Yes — M2 is the most common material for twist drills and machine taps. It performs well in steel, cast iron, aluminium, and plastics. For very hard materials or high-production work, coated M2 (TiN, TiAlN) or solid carbide tooling is preferred.
Welding M2 is very difficult and generally not recommended. If required for die repair, preheat to 350–450°C, use a matching HSS filler rod, and temper immediately after welding before the part cools. Most tool shops replace rather than weld M2 tools.
