Steel M3-1 HT 64-66 HRC
Hardness band
UNS T11313 · AISI/SAE M3 Class 1 · GB W6Mo5Cr4V3
HT 64-66 HRC = hardened & tempered to 64–66 HRC
Full austenitizing (~1210–1230 °C) with triple temper near the secondary-hardness peak; use for drills, taps, broaches and form tools where edge life outranks toughness.
Values for the HT 64-66 HRC condition
Other M3-1 tempers and conditions
M3-1 is listed in 4 conditions; see the grade overview at M3-1.
- Annealed
- HT 62-64 HRC
- HT 64-66 HRC
- HT+CRYO
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault spheroidize annealed bar/blank stock | Standard as-supplied condition for bars, blanks and forging stock; soft enough to machine before hardening. | 550 | 870 | 20 | 235 HB | 22 W/m·K |
Hardened & tempered to 62–64 HRC | Austenitize ~1190–1210 °C, oil/salt/vacuum quench, triple temper ~550–565 °C; choose when interrupted cuts or shock loading dominate. | 1,900 | 2,200 | 1 | 63 HRC | 24 W/m·K |
HT 64-66 HRCThis page Hardened & tempered to 64–66 HRC | Full austenitizing (~1210–1230 °C) with triple temper near the secondary-hardness peak; use for drills, taps, broaches and form tools where edge life outranks toughness. | 2,100 | 2,400 | 0.5 | 65 HRC | 24 W/m·K |
Hardened, deep-cryogenic treated and tempered | Adds a −80 to −196 °C soak between quench and temper to convert retained austenite; gives ~1 HRC more and better dimensional stability for precision tools. | 2,150 | 2,400 | 0.5 | 66 HRC | 2.5 % IACS |
What is M3-1 HT 64-66 HRC?
M3-1 HT 64-66 HRC is M3-1 heat treated to HT 64-66 HRC — full austenitizing (~1210–1230 °C) with triple temper near the secondary-hardness peak; use for drills, taps, broaches and form tools where edge life outranks toughness. M3-1 HT 64-66 HRC has a yield strength of 2,100 MPa (305 ksi) and a tensile strength of 2,400 MPa (348 ksi) — stronger than 100% of steel grades. Elongation at break is 0.5% and the elastic modulus is 217 GPa (31.5 Msi). M3-1 HT 64-66 HRC has a density of 8.05 g/cm³ (0.291 lb/in³), heavier than 96% of steel grades. It melts at 1,250°C (2,282 °F). Annealed is the default condition FabDigit quotes; HT 64-66 HRC is available on request or by drawing note.
Advantages
- High strength — 2,100 MPa (305 ksi), better than 100% of steel grades
- High service temperature — 550°C (1,022 °F), better than 95% of steel grades
Limitations
- Limited ductility — 0.5%, worse than 100% of steel grades
- Difficult to machine — 4/100, worse than 100% of steel grades
- Difficult to weld — 8/100, worse than 99% of steel grades
- Low electrical conductivity — 2.9 % IACS, worse than 93% of steel grades
- High embodied carbon — 3.2 kg CO₂/kg, worse than 92% of steel grades
M3-1 HT 64-66 HRC properties
Typical room-temperature values for M3-1 HT 64-66 HRC; 17 are specific to this condition. Other listed values are M3-1 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
M3-1 HT 64-66 HRC has a density of 8.05 g/cm³ (0.291 lb/in³), heavier than 96% of steel grades. It melts at 1,250°C (2,282 °F).
Mechanical15
M3-1 HT 64-66 HRC has a yield strength of 2,100 MPa (305 ksi) and a tensile strength of 2,400 MPa (348 ksi) — stronger than 100% of steel grades. Elongation at break is 0.5% and the elastic modulus is 217 GPa (31.5 Msi).
Thermal6
M3-1 HT 64-66 HRC is rated for continuous service to 550°C (1,022 °F). It conducts heat at 24 W/m·K (13.9 BTU/hr·ft·°F), worse than 90% of steel grades. Thermal expansion is 10.3 µm/m·K (5.72 µin/in·°F).
Electrical3
M3-1 HT 64-66 HRC conducts electricity at 2.9 % IACS, worse than 93% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of M3-1 HT 64-66 HRC takes about 48 MJ of energy and emits 3.2 kg of CO₂ — more than 93% of steel grades. Typical recycled content is 35%.
Manufacturability8
M3-1 HT 64-66 HRC's machinability is not recommended (4/100, worse than 100% of steel grades); weldability not recommended (8/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with M3-1 HT 64-66 HRC
Is M3-1 easy to machine?
Machine only in the annealed condition with rigid setups and cobalt/carbide tooling; the 2.5 % V raises abrasive MC carbide content, so expect ~40 % of AISI 1212 and grind hardened parts with CBN or SG-alumina wheels.
Can M3-1 be welded?
Not a structural weld metal — repair only by TIG/laser with matching HSS filler at 480–540 °C preheat followed by immediate re-temper to avoid quench cracks.
Can M3-1 be formed, bent or molded?
Hot work 1050–1120 °C, stop above ~900 °C and slow-cool/anneal at 850–900 °C; no meaningful cold forming.
What surface finishes work on M3-1?
Cannot be anodized; use steam oxide, black oxide, nitriding or TiN/TiAlN PVD (below the 550 °C temper temperature) plus oiling for rust protection.
M3-1 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 |
|---|---|---|
| CASTM A600 M3 Class 1 | 1 – 1.1 | 1.05 |
| Mn | 0.15 – 0.4 | 0.3 |
| Si | 0.2 – 0.45 | 0.3 |
| Cr | 3.75 – 4.5 | 4.1 |
| Vhigher than M2; source of the extra wear resistance | 2.25 – 2.75 | 2.5 |
| W | 5 – 6.75 | 6 |
| Mo | 4.75 – 6.5 | 5.5 |
| Coresidual maximum | ≤ 0.75 | — |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
M3-1 HT 64-66 HRC — frequently asked
What is M3-1 HT 64-66 HRC used for?
M3-1 HT 64-66 HRC is typically used for form tools, broaches, reamers and high-volume drills. In short: higher-vanadium M2 upgrade; longer edge life; wear-biased general-purpose HSS.
What is the yield strength of M3-1 HT 64-66 HRC?
M3-1 HT 64-66 HRC has a typical yield strength of 2,100 MPa (305 ksi) and a tensile strength of 2,400 MPa (348 ksi) — stronger than 100% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is M3-1 HT 64-66 HRC easy to machine?
Not especially — machinability is rated not recommended (4/100, worse than 100% of steel grades). Machine only in the annealed condition with rigid setups and cobalt/carbide tooling; the 2.5 % V raises abrasive MC carbide content, so expect ~40 % of AISI 1212 and grind hardened parts with CBN or SG-alumina wheels.
Can M3-1 HT 64-66 HRC be welded?
Not readily — weldability is rated not recommended (8/100). Not a structural weld metal — repair only by TIG/laser with matching HSS filler at 480–540 °C preheat followed by immediate re-temper to avoid quench cracks.
What surface finishes work on M3-1 HT 64-66 HRC?
Cannot be anodized; use steam oxide, black oxide, nitriding or TiN/TiAlN PVD (below the 550 °C temper temperature) plus oiling for rust protection.
Can M3-1 HT 64-66 HRC be formed, bent or molded?
Hot work 1050–1120 °C, stop above ~900 °C and slow-cool/anneal at 850–900 °C; no meaningful cold forming.
What is the maximum service temperature of M3-1 HT 64-66 HRC?
M3-1 HT 64-66 HRC is rated for continuous use to about 550°C (1,022 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM A600 — Standard Specification for Tool Steel High Speed — ASTM International (2016)
- JIS G4403 — High speed tool steel (SKH52) — Japanese Standards Association (2015)
- GB/T 9943 — (W6Mo5Cr4V3) — SAC (2008)
- ASM Handbook Vol.1: Properties and Selection — Tool Steels — ASM International (1990)
- ASM Handbook Vol.16: Machining — ASM International (1989)
- High-speed steel grade datasheets (M2/M3 class) — Böhler / Erasteel (2022)
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.