# M2 high-speed steel

Molybdenum-tungsten high-speed tool steel: product identity, supplied condition, heat-treatment evidence and cutting-tool qualification.

Reviewed: 2026-11-01

Tags: materials, steel, tool-steel, high-speed-steel

## Identity and purchase specification

For **BÖHLER S600**, the treatment section gives **1100–1210°C austenitizing** and an **80-second hold after complete heating, maximum 150 seconds**. The separate **180-second hold at 1210°C** belongs to the CCT experiment. Follow the treatment guidance for the actual stock and retain the CCT hold as a test condition. [BÖHLER S600 treatment and CCT data](https://www.bohler-edelstahl.com/app/uploads/sites/248/productdb/api/s600_en_gb.pdf)

M2 is a molybdenum-tungsten high-speed tool steel identified as **UNS T11302**. Carpenter's nominal analysis gives carbon 0.82%, chromium 4.25%, molybdenum 5%, tungsten 6.25% and vanadium 1.8%, with iron balance and other elements. Nominal producer chemistry is not a complete specification acceptance table. [Carpenter M2 product page](https://www.carpentertechnology.com/alloy-finder/m2)

ASTM's official scope identifies **A600-92a(2024)** as a high-speed tool-steel specification covering M2 among its molybdenum types. It covers specified annealed hot-rolled and cold-finished forms used primarily to fabricate tools. That material specification does not qualify a finished drill, cutter or die for a particular operation. [ASTM A600 official scope](https://store.astm.org/standards/a600)

BÖHLER S600 identifies **1.3343 / HS6-5-2C**, air-melted or air-melted-plus-ESR routes, and a **long-product** data restriction despite listing plate. Preserve that scope when using its data. [BÖHLER S600](https://www.bohler-edelstahl.com/app/uploads/sites/248/productdb/api/s600_en_gb.pdf)

Specify exact grade or producer product, standard edition, stock form, dimensions, delivery condition, surface allowance and inspection documents. Preserve heat/lot identity through cutting and thermal processing. A label saying only “HSS” does not establish M2 chemistry, and an M2 certificate does not establish a tool's coating, edge geometry or final hardness.

## Application and failure mechanism

Universal Stainless describes M2 primarily for cutting-tool applications and separately offers plate in a producer-defined dimensional range. Availability of a plate product does not make a long-product heat-treatment dataset a plate guarantee. [Universal Stainless M2](https://www.univstainless.com/m2/)

For a cutter, identify the work material, cutting mode, interruptions, rigidity, cooling, edge geometry and acceptable wear criterion. Separate abrasive wear, adhesion, edge chipping, gross fracture and thermal softening. A harder tool may resist one mechanism while performing worse against another. Choose the tool system and process together; the grade name supplies neither a universal cutting speed nor a guaranteed service interval.

## Supplied condition is not finished-tool hardness

S600 lists annealed delivery at **≤280 HB**, tensile strength **≤950 MPa**, and separately hardened-and-tempered bars, BHT, at **≥62 HRC**. [BÖHLER delivery conditions](https://www.bohler-edelstahl.com/app/uploads/sites/248/productdb/api/s600_en_gb.pdf)

Specify final hardness and test location, plus any decarburization, retained austenite, carbide distribution or core uniformity requirements.

Carpenter's technical bulletin labels its mechanical information typical/average and describes hot-hardness behavior using different prior tempering conditions. A room-temperature hardness reading and hardness measured while hot answer different questions. [Carpenter M2 technical bulletin](https://www.carpentertechnology.com/hubfs/7407324/Material%20Saftey%20Data%20Sheets/M2%20.pdf)

## Heat treatment: preserve timing and specimen basis

For S600, BÖHLER gives **1100–1210°C austenitizing**, holding **80 seconds after complete heating, maximum 150 seconds**, followed by the listed quench choices. Its tempering section recommends **550–570°C**, at least two hours and three cycles with cooling to room temperature. The tempering chart identifies **vacuum, 3 × 2 hours and a 25 mm square specimen**. These are named-product reference conditions, not a cycle for arbitrary stock. [BÖHLER thermal guidance and chart footer](https://www.bohler-edelstahl.com/app/uploads/sites/248/productdb/api/s600_en_gb.pdf)

The same sheet's CCT diagram lists a 180-second hold at 1210°C. Treat a diagram's experimental basis separately from the treatment section's stated maximum; do not merge them into a new shop instruction. [BÖHLER CCT basis](https://www.bohler-edelstahl.com/app/uploads/sites/248/productdb/api/s600_en_gb.pdf)

Carpenter's historical M2 bulletin gives a different furnace-hardening range, **1177–1232°C**, and warns of decarburization during thermal processing. It discusses multiple tempers with intermediate cooling. Those instructions belong to that product and source edition, not an averaged combination with S600. [Carpenter heat-treatment guidance](https://www.carpentertechnology.com/hubfs/7407324/Material%20Saftey%20Data%20Sheets/M2%20.pdf)

## Finishing, regrinding and repair

Plan rough machining, stress relief where needed, heat treatment and final grinding as a sequence. Establish allowable stock removal, final dimensions and edge/surface acceptance before processing. Inspect for distortion and surface damage at the stage where correction remains possible. A dimensionally correct tool can still have an unacceptable working surface.

Carpenter says its machining tables are guidance for initial setup and require adjustment for each job. Those stock-machining data should not be confused with speeds for using the finished M2 cutter on another material. [Carpenter machinability scope](https://www.carpentertechnology.com/hubfs/7407324/Material%20Saftey%20Data%20Sheets/M2%20.pdf)

For regrinding, specify the recovered geometry, surface condition and any recoating requirement. Count accepted output after each regrind separately when estimating tool economics. For repair welding, EDM or a later coating heat cycle, obtain product-specific processing guidance and verify the affected tool rather than assuming that its original certificate still describes the local condition.

## Bounded mass estimate

Carpenter lists density **0.294 lb/in³**. For an ideal 0.5 in diameter, 6 in long solid blank, original arithmetic gives:

`V = π × 0.5² / 4 × 6 = 1.1781 in³`

`m = 1.1781 × 0.294 ≈ 0.3464 lb`.

This excludes tolerances, flute removal, holes and coatings. It supports an initial stock estimate, not a finished-tool mass or acceptance test. [Carpenter physical properties](https://www.carpentertechnology.com/hubfs/7407324/Material%20Saftey%20Data%20Sheets/M2%20.pdf)

## Source editions and related reference

BÖHLER's inspected sheet prints **S600 EN_GB – 09.2026**. Carpenter's bulletin prints **Edition Date 11/01/1988** and **©2020**; the copyright is not evidence of a new technical edition. ASTM identifies **A600-92a(2024)**, with its record updated 14 March 2024. No separate technical revision date was verified for the producer webpages. Confirm current contractual requirements independently of this draft's review date.

[Grades, tempers and conditions](../grades-tempers-and-conditions.md)