Steel M4 H&T 64-66 HRC
Hardness band
AISI/SAE M4 · UNS T11304 · EN S6-5-4 · JIS SKH54 · GB W6Mo5Cr4V4
H&T 64-66 HRC = hardened & Tempered 64–66 HRC
Maximum wear resistance and red hardness for cutting tools; accept lower toughness and chipping risk.
Values for the H&T 64-66 HRC condition
Other M4 tempers and conditions
M4 is listed in 6 conditions; see the grade overview at M4.
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 |
H&T 64-66 HRCThis page 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 H&T 64-66 HRC?
M4 H&T 64-66 HRC is M4 heat treated to H&T 64-66 HRC — maximum wear resistance and red hardness for cutting tools; accept lower toughness and chipping risk. M4 H&T 64-66 HRC has a yield strength of 2,050 MPa (297 ksi) and a tensile strength of 2,350 MPa (341 ksi) — stronger than 100% of steel grades. Elongation at break is 1% and the elastic modulus is 221 GPa (32.1 Msi). M4 H&T 64-66 HRC 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). Annealed is the default condition FabDigit quotes; H&T 64-66 HRC is available on request or by drawing note.
Advantages
- High strength — 2,050 MPa (297 ksi), better than 100% of steel grades
- High service temperature — 590°C (1,094 °F), better than 97% of steel grades
Limitations
- Low fracture toughness — 14 MPa·√m (12.7 ksi·√in), worse than 100% of steel grades
- Difficult to machine — 3/100, worse than 100% of steel grades
- Difficult to weld — 5/100, worse than 100% of steel grades
- Limited formability — 1/100, worse than 100% of steel grades
- Limited ductility — 1%, worse than 99% of steel grades
M4 H&T 64-66 HRC properties
Typical room-temperature values for M4 H&T 64-66 HRC; 21 are specific to this condition. Other listed values are M4 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
M4 H&T 64-66 HRC 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 H&T 64-66 HRC has a yield strength of 2,050 MPa (297 ksi) and a tensile strength of 2,350 MPa (341 ksi) — stronger than 100% of steel grades. Elongation at break is 1% and the elastic modulus is 221 GPa (32.1 Msi).
Thermal6
M4 H&T 64-66 HRC is rated for continuous service to 590°C (1,094 °F). It conducts heat at 20 W/m·K (11.6 BTU/hr·ft·°F), worse than 96% of steel grades. Thermal expansion is 11 µm/m·K (6.11 µin/in·°F).
Electrical3
M4 H&T 64-66 HRC conducts electricity at 2.6 % IACS, worse than 97% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of M4 H&T 64-66 HRC 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 H&T 64-66 HRC's machinability is not recommended (3/100, worse than 100% of steel grades); weldability not recommended (5/100); formability not recommended (1/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with M4 H&T 64-66 HRC
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.
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.
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 | — |
M4 H&T 64-66 HRC — frequently asked
What is M4 H&T 64-66 HRC used for?
M4 H&T 64-66 HRC is typically used for broaches, cutting tools and milling cutters. In short: high-impact toughness.
What is the yield strength of M4 H&T 64-66 HRC?
M4 H&T 64-66 HRC has a typical yield strength of 2,050 MPa (297 ksi) and a tensile strength of 2,350 MPa (341 ksi) — stronger than 100% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is M4 H&T 64-66 HRC easy to machine?
Not especially — machinability is rated not recommended (3/100, worse than 100% 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 H&T 64-66 HRC be welded?
Not readily — weldability is rated not recommended (5/100). 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 H&T 64-66 HRC?
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 H&T 64-66 HRC 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 H&T 64-66 HRC?
M4 H&T 64-66 HRC is rated for continuous use to about 590°C (1,094 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in M4 H&T 64-66 HRC?
Yes — M4 H&T 64-66 HRC 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.