Steel M4
AISI/SAE M4 · UNS T11304 · EN S6-5-4 · JIS SKH54 · GB W6Mo5Cr4V4
M4 is a molybdenum-series high-carbon, high-vanadium high-speed steel (about 1.3% C, 6% W, 5% Mo, 4% Cr, 4% V; S6-5-4 / SKH54) whose large volume of hard MC vanadium carbides gives 62–65 HRC after hardening and tempering, with very high abrasion resistance and good red hardness.
Values for the Annealed condition
M4 tempers and conditions
M4 is supplied in 6 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault spheroidize annealed, 223–255 HB | Standard supply condition for bar and flats; machine tool blanks in this state, then harden. | 550 | 880 | 12 | 24 HRC | — |
Stress relieved after rough machining (~650–700 °C, annealed base) | Intermediate step for large or asymmetric tools to minimise distortion during hardening. | 560 | 890 | 11 | 25 HRC | 2.9 % IACS |
Hardened & Tempered 60–62 HRC | Choose when impact/chipping dominates over abrasive wear, e.g. heavy blanking and trim dies. | 1,900 | 2,150 | 2 | 61 HRC | 2.7 % IACS |
deep freeze (−80 to −196 °C) between tempers | Adds ~0.5–1 HRC and improves dimensional stability by converting retained austenite; used for precision gauges and long-run punches. | 2,000 | 2,300 | 1 | 64 HRC | 2.7 % IACS |
Hardened & Tempered 64–66 HRC | Maximum wear resistance and red hardness for cutting tools; accept lower toughness and chipping risk. | 2,050 | 2,350 | 1 | 65 HRC | 2.6 % IACS |
62–64 HRC (austenitize ~1200 °C, triple temper ~550 °C) | General working hardness for cold-work punches, form tools and broaches — best wear/toughness balance. | 2,200 | 63 HRC | — |
What is M4?
M4 is a molybdenum-series high-carbon, high-vanadium high-speed steel (about 1.3% C, 6% W, 5% Mo, 4% Cr, 4% V; S6-5-4 / SKH54) whose large volume of hard MC vanadium carbides gives 62–65 HRC after hardening and tempering, with very high abrasion resistance and good red hardness. It is used for cold blanking and trimming dies, gear hobs, broaches, saw blades and high-wear punches, and is stocked annealed at 250 HB or hardened to 60–66 HRC. Grindability and machinability are poor, toughness is below M2, and with only 4% Cr it rusts, so protected storage and closely controlled heat treatment are required. M4 has a density of 7.97 g/cm³ (0.288 lb/in³), heavier than 94% of steel grades. It melts at 1,250°C (2,282 °F). M4 has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 71% of steel grades. Elongation at break is 12% and the elastic modulus is 217 GPa (31.5 Msi).
What is M4 used for?
- Broaches
- Cutting tools
- Milling cutters
Limitations
- Low fracture toughness — 22 MPa·√m (20 ksi·√in), worse than 98% of steel grades
- High embodied carbon — 4.2 kg CO₂/kg, worse than 95% of steel grades
- Poor heat conductor — 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 93% of steel grades
- Low electrical conductivity — 2.9 % IACS, worse than 93% of steel grades
- Difficult to machine — 25/100, worse than 93% of steel grades
M4 properties
Typical room-temperature values for M4-Annealed; bars are the position among steel grades.
Physical3
M4 has a density of 7.97 g/cm³ (0.288 lb/in³), heavier than 94% of steel grades. It melts at 1,250°C (2,282 °F).
Mechanical14
M4 has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 71% of steel grades. Elongation at break is 12% and the elastic modulus is 217 GPa (31.5 Msi).
Thermal6
M4 is rated for continuous service to 400°C (752 °F). It conducts heat at 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 93% of steel grades. Thermal expansion is 11 µm/m·K (6.11 µin/in·°F).
Electrical3
M4 conducts electricity at 2.9 % IACS, worse than 93% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of M4 takes about 58 MJ of energy and emits 4.2 kg of CO₂ — more than 95% of steel grades. Typical recycled content is 35%.
Manufacturability8
M4's machinability is poor (25/100, worse than 93% of steel grades); weldability poor (15/100); formability not recommended (12/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. M4 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with M4
Is M4 easy to machine?
Machine only in the annealed state with rigid setups, low speeds and carbide or coated-carbide tooling; the 4% V carbides also make grinding difficult — use SG/CBN wheels and light passes.
Can M4 be welded?
Not a structural weld grade; repair-weld only with matched HSS filler, preheat 480–540 °C, weld hot and re-temper immediately to avoid cracking.
Can M4 be formed, bent or molded?
Hot forge 1000–1120 °C (stop above ~950 °C) and slow cool, then full spheroidize anneal at ~870 °C; no meaningful cold forming.
Manufacturability
The process limits FabDigit applies to M4. Every M4 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Fair25 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
M4 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C | 1.25 – 1.4 | 1.32 |
| Mn | 0.15 – 0.4 | 0.3 |
| Si | 0.2 – 0.45 | 0.3 |
| Cr | 3.75 – 4.75 | 4.25 |
| Vhigh V gives MC carbides / wear resistance | 3.75 – 4.5 | 4 |
| W | 5.25 – 6.5 | 5.75 |
| Mo | 4.25 – 5.5 | 4.75 |
| P | ≤ 0.03 | |
| Smax; resulfurized M4 variants allow 0.06–0.15 | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on M4?
Finish grind after hardening, then nitride, black-oxide, steam-treat or PVD-coat (TiN/TiAlN) for wear and rust protection; oil or wax bare surfaces in storage.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel M4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T11304
- AISI / SAE
- M-4
- EN / DIN / Werkstoff-Nr.
- S6-5-4
- GB (China)
- W6Mo5Cr4V4
- JIS
- SKH54
How much does M4 cost?
M4 is a specialty-cost steel ($$$$$), pricier than about 99% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
M4 — frequently asked
What is M4 used for?
M4 is typically used for broaches, cutting tools and milling cutters. In short: high-impact toughness.
What is the yield strength of M4?
M4 has a typical yield strength of 550 MPa (79.8 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 71% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is M4 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 93% of steel grades). Machine only in the annealed state with rigid setups, low speeds and carbide or coated-carbide tooling; the 4% V carbides also make grinding difficult — use SG/CBN wheels and light passes.
Can M4 be welded?
Not readily — weldability is rated poor (15/100). Not a structural weld grade; repair-weld only with matched HSS filler, preheat 480–540 °C, weld hot and re-temper immediately to avoid cracking.
What surface finishes work on M4?
Finish grind after hardening, then nitride, black-oxide, steam-treat or PVD-coat (TiN/TiAlN) for wear and rust protection; oil or wax bare surfaces in storage.
Can M4 be formed, bent or molded?
Hot forge 1000–1120 °C (stop above ~950 °C) and slow cool, then full spheroidize anneal at ~870 °C; no meaningful cold forming.
What is the maximum service temperature of M4?
M4 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does M4 cost?
M4 is a specialty-cost steel ($$$$$), pricier than about 99% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in M4?
Yes — M4 is available for CNC machining; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A600 — Standard Specification for Tool Steel High Speed — ASTM International (2016)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Tool Steels, 5th Edition (Roberts, Krauss, Kennedy) — ASM International (1998)
- CPM M4 / M4 High Speed Steel data sheet — Crucible Industries (2020)
- High speed steel grade data (M4 / HS6-5-4) — Erasteel (2021)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.