Steel M3-2-HT64
Heat-treated state
UNS T11323 · AISI/SAE M3 Class 2
HT64 = hardened & triple tempered
Normal working hardness for drills, end mills, broaches and form tools needing maximum abrasion resistance.
Values for the HT64 condition
Other M3-2 tempers and conditions
M3-2 is listed in 4 conditions; see the grade overview at M3-2.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Hardened & triple tempered | Salt-bath/vacuum hardening near 1220 °C for maximum wear life in light, rigid cuts; toughness is minimal. | — | — | — | 66 HRC | — |
ANNDefault Annealed | Stock condition for machining tool blanks before hardening; no wear performance. | 550 | 880 | 12 | 250 HB | 24 W/m·K |
Hardened & triple tempered | Lower austenitizing (~1180 °C) for interrupted cuts, taps and larger cross-sections where chipping is the risk. | — | 2,200 | 0.5 | 63 HRC | 22 W/m·K |
HT64This page Hardened & triple tempered | Normal working hardness for drills, end mills, broaches and form tools needing maximum abrasion resistance. | — | 2,400 | 0.3 | 65 HRC | 22 W/m·K |
What is M3-2-HT64?
M3-2-HT64 is M3-2 heat treated to HT64 — normal working hardness for drills, end mills, broaches and form tools needing maximum abrasion resistance. M3-2-HT64 has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 2,400 MPa (348 ksi) — stronger than 71% of steel grades. Elongation at break is 0.3% and the elastic modulus is 227 GPa (32.9 Msi). M3-2-HT64 has a density of 8.15 g/cm³ (0.294 lb/in³), heavier than 97% of steel grades. It melts at 1,240°C (2,264 °F). ANN is the default condition FabDigit quotes; HT64 is available on request or by drawing note.
Advantages
- High service temperature — 560°C (1,040 °F), better than 96% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Limited ductility — 0.3%, worse than 100% of steel grades
- Difficult to machine — 4/100, worse than 100% of steel grades
- Limited formability — 1/100, worse than 100% of steel grades
- Difficult to weld — 8/100, worse than 99% of steel grades
- Poor heat conductor — 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 93% of steel grades
M3-2-HT64 properties
Typical room-temperature values for M3-2-HT64; 20 are specific to this condition. Other listed values are M3-2 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
M3-2-HT64 has a density of 8.15 g/cm³ (0.294 lb/in³), heavier than 97% of steel grades. It melts at 1,240°C (2,264 °F).
Mechanical14
M3-2-HT64 has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 2,400 MPa (348 ksi) — stronger than 71% of steel grades. Elongation at break is 0.3% and the elastic modulus is 227 GPa (32.9 Msi).
Thermal6
M3-2-HT64 is rated for continuous service to 560°C (1,040 °F). It conducts heat at 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 93% of steel grades. Thermal expansion is 10.6 µm/m·K (5.89 µin/in·°F).
Electrical3
M3-2-HT64 conducts electricity at 3.2 % IACS, worse than 87% of steel grades.
Chemical & Environmental2
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of M3-2-HT64 takes about 42 MJ of energy and emits 3.2 kg of CO₂ — more than 92% of steel grades. Typical recycled content is 40%.
Manufacturability7
M3-2-HT64's machinability is not recommended (4/100, worse than 100% of steel grades); weldability not recommended (8/100); formability not recommended (1/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with M3-2-HT64
Is M3-2 easy to machine?
Machine only in the annealed condition with rigid setups, cobalt-HSS or coated carbide and generous coolant; the ~3 % V MC carbides also make grinding slow — use SG/CBN wheels and light dressing.
Can M3-2 be welded?
Not a structural weldable steel; repair-weld only with 500–550 °C preheat, matching HSS or Co-alloy filler, immediate re-temper at 540–560 °C ×3.
Can M3-2 be formed, bent or molded?
Hot work 900–1100 °C with slow cooling and immediate anneal (860–900 °C, ≤20 °C/h to 700 °C); no meaningful cold forming.
What surface finishes work on M3-2?
Harden 1190–1220 °C (vacuum/salt), quench, triple temper 540–560 °C ×1 h to 64–66 HRC; finish with steam-oxide, nitrocarburizing or TiN/TiAlN PVD (≤500 °C) plus oil film for rust protection.
M3-2 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 | 1.15 – 1.25 | 1.2 |
| Mn | 0.15 – 0.4 | 0.3 |
| Si | 0.2 – 0.45 | 0.3 |
| Cr | 3.75 – 4.5 | 4.1 |
| W | 5 – 6.75 | 6 |
| Mo | 4.75 – 6.5 | 5.5 |
| VClass 2 = higher V than M3 Class 1 | 2.75 – 3.75 | 3.1 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
M3-2-HT64 — frequently asked
What is M3-2-HT64 used for?
M3-2-HT64 is typically used for cutoff tools, threading dies, heavy-duty reamers and broaches. In short: highest-wear general-purpose HSS; about 3 % vanadium; hardest of family to grind.
What is the yield strength of M3-2-HT64?
M3-2-HT64 has a typical yield strength of 550 MPa (79.8 ksi) and a tensile strength of 2,400 MPa (348 ksi) — stronger than 71% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is M3-2-HT64 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, cobalt-HSS or coated carbide and generous coolant; the ~3 % V MC carbides also make grinding slow — use SG/CBN wheels and light dressing.
Can M3-2-HT64 be welded?
Not readily — weldability is rated not recommended (8/100). Not a structural weldable steel; repair-weld only with 500–550 °C preheat, matching HSS or Co-alloy filler, immediate re-temper at 540–560 °C ×3.
What surface finishes work on M3-2-HT64?
Harden 1190–1220 °C (vacuum/salt), quench, triple temper 540–560 °C ×1 h to 64–66 HRC; finish with steam-oxide, nitrocarburizing or TiN/TiAlN PVD (≤500 °C) plus oil film for rust protection.
Can M3-2-HT64 be formed, bent or molded?
Hot work 900–1100 °C with slow cooling and immediate anneal (860–900 °C, ≤20 °C/h to 700 °C); no meaningful cold forming.
What is the maximum service temperature of M3-2-HT64?
M3-2-HT64 is rated for continuous use to about 560°C (1,040 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM A600 — Tool Steel, High Speed — ASTM International (2021)
- JIS G 4403 SKH53 — JSA (2015)
- GB/T 9943 (W6Mo5Cr4V3) — SAC (2008)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (Tool Steels) — ASM International (1990)
- HS6-5-3 / 1.3344 high speed steel data sheet — Böhler / Erasteel (2020)
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.