Steel M62 QT64-66
Hardness band
AISI/SAE M62 · UNS T11362
QT64-66 = q&T 64–66 HRC
Choose for interrupted cuts, larger cutters and cold-work punches where edge chipping is the risk.
Values for the QT64-66 condition
Other M62 tempers and conditions
M62 is listed in 5 conditions; see the grade overview at M62.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard mill-supplied condition for machining tool blanks before hardening. | 560 | 900 | 12 | 25 HRC | 24 W/m·K |
Annealed, centreless ground / precision-ground bar | Pick when tool blanks need close diameter tolerance and clean surface before hardening. | 560 | 900 | 12 | 25 HRC | 3.1 % IACS |
Q&T + surface treatment | Finished cutting-tool condition where a coating adds lubricity and further raises abrasive/adhesive wear life. | 2,000 | 2,100 | 0.5 | 67 HRC | 2.8 % IACS |
Q&T 66–68 HRC | Standard working condition: maximum hot hardness and wear resistance for drilling/milling superalloys and hardened steels. | — | 2,100 | 0.2 | 67 HRC | 20 W/m·K |
QT64-66This page Q&T 64–66 HRC | Choose for interrupted cuts, larger cutters and cold-work punches where edge chipping is the risk. | — | 2,300 | 0.5 | 65 HRC | 21 W/m·K |
What is M62 QT64-66?
M62 QT64-66 is M62 heat treated to QT64-66 — choose for interrupted cuts, larger cutters and cold-work punches where edge chipping is the risk. M62 QT64-66 has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 2,300 MPa (334 ksi) — stronger than 73% of steel grades. Elongation at break is 0.5% and the elastic modulus is 221 GPa (32.1 Msi). M62 QT64-66 has a density of 8.16 g/cm³ (0.295 lb/in³), heavier than 98% of steel grades. It melts at 1,230°C (2,246 °F). A is the default condition FabDigit quotes; QT64-66 is available on request or by drawing note.
Advantages
- High service temperature — 600°C (1,112 °F), better than 98% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Limited ductility — 0.5%, worse than 100% of steel grades
- Difficult to machine — 8/100, worse than 100% of steel grades
- Limited formability — 2/100, worse than 100% of steel grades
- Difficult to weld — 10/100, worse than 99% of steel grades
- High embodied carbon — 5.6 kg CO₂/kg, worse than 98% of steel grades
M62 QT64-66 properties
Typical room-temperature values for M62 QT64-66; 15 are specific to this condition. Other listed values are M62 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
M62 QT64-66 has a density of 8.16 g/cm³ (0.295 lb/in³), heavier than 98% of steel grades. It melts at 1,230°C (2,246 °F).
Mechanical15
M62 QT64-66 has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 2,300 MPa (334 ksi) — stronger than 73% of steel grades. Elongation at break is 0.5% and the elastic modulus is 221 GPa (32.1 Msi).
Thermal6
M62 QT64-66 is rated for continuous service to 600°C (1,112 °F). It conducts heat at 21 W/m·K (12.1 BTU/hr·ft·°F), worse than 95% of steel grades. Thermal expansion is 10.8 µm/m·K (6 µin/in·°F).
Electrical3
M62 QT64-66 conducts electricity at 3.1 % IACS, worse than 89% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of M62 QT64-66 takes about 78 MJ of energy and emits 5.6 kg of CO₂ — more than 98% of steel grades. Typical recycled content is 30%.
Manufacturability8
M62 QT64-66's machinability is not recommended (8/100, worse than 100% of steel grades); weldability not recommended (10/100); formability not recommended (2/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with M62 QT64-66
Is M62 easy to machine?
Machine only in the annealed condition with rigid setups, low speeds and cobalt/carbide tooling; after hardening only grinding (CBN or seeded-gel alumina wheels) or EDM is practical.
Can M62 be welded?
Essentially non-weldable structurally; repair only by preheated (450–550 °C) TIG/laser build-up with matching HSS filler followed by immediate multiple tempers.
Can M62 be formed, bent or molded?
Hot forge 1050–1120 °C with slow cooling and full anneal (≈870 °C, controlled cool) afterwards; no cold forming.
What surface finishes work on M62?
Salt-bath or vacuum harden at ~1180–1210 °C, triple temper at 540–560 °C, then steam oxide, nitride or TiN/TiAlN PVD; oil or coat for rust protection in storage.
M62 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 – 1.35 | 1.3 |
| Mn | 0.15 – 0.4 | 0.3 |
| Si | 0.15 – 0.4 | 0.3 |
| Cr | 3.5 – 4 | 3.75 |
| V | 1.8 – 2.1 | 2 |
| W | 5.75 – 6.5 | 6.25 |
| Mo | 10 – 11 | 10.5 |
| Co | 11 – 12 | 11.5 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
M62 QT64-66 — frequently asked
What is M62 QT64-66 used for?
M62 QT64-66 is typically used for drills and reamers for hard materials, heavy-duty cutting tools and broaches for high-strength alloys. In short: high-vanadium wear resistance; cobalt HSS to 68 HRC; demanding to grind.
What is the yield strength of M62 QT64-66?
M62 QT64-66 has a typical yield strength of 560 MPa (81.2 ksi) and a tensile strength of 2,300 MPa (334 ksi) — stronger than 73% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is M62 QT64-66 easy to machine?
Not especially — machinability is rated not recommended (8/100, worse than 100% of steel grades). Machine only in the annealed condition with rigid setups, low speeds and cobalt/carbide tooling; after hardening only grinding (CBN or seeded-gel alumina wheels) or EDM is practical.
Can M62 QT64-66 be welded?
Not readily — weldability is rated not recommended (10/100). Essentially non-weldable structurally; repair only by preheated (450–550 °C) TIG/laser build-up with matching HSS filler followed by immediate multiple tempers.
What surface finishes work on M62 QT64-66?
Salt-bath or vacuum harden at ~1180–1210 °C, triple temper at 540–560 °C, then steam oxide, nitride or TiN/TiAlN PVD; oil or coat for rust protection in storage.
Can M62 QT64-66 be formed, bent or molded?
Hot forge 1050–1120 °C with slow cooling and full anneal (≈870 °C, controlled cool) afterwards; no cold forming.
What is the maximum service temperature of M62 QT64-66?
M62 QT64-66 is rated for continuous use to about 600°C (1,112 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between M62-A and M62 QT-SURF?
A is the default condition — standard mill-supplied condition for machining tool blanks before hardening. QT-SURF: finished cutting-tool condition where a coating adds lubricity and further raises abrasive/adhesive wear life. Yield strength is 560 MPa in A versus 2,000 MPa in QT-SURF.
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)
- ASM Handbook Vol.16: Machining — ASM International (1989)
- Tool Steels, 5th ed. — ASM International (1998)
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.