Steel M34 HT-65
Heat-treated state
AISI/SAE M34 · UNS T11334
HT-65 = hT 64–66 HRC
General-purpose hardened condition for drills, taps, end mills and broaches with a good hardness/toughness balance.
Values for the HT-65 condition
Other M34 tempers and conditions
M34 is listed in 5 conditions; see the grade overview at M34.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard supply condition for machining tool blanks before hardening. | 560 | 880 | 22 | 235 HB | — |
Cold drawn / ground annealed bar | Choose for close-tolerance ground drill/tap blanks that will be hardened after fluting. | 700 | 950 | 14 | 25 HRC | 3.2 % IACS |
HT + surface treated | Finished-tool condition where a hard, low-friction surface layer is added to the hardened core for higher wear and galling resistance. | 2,050 | 2,300 | 0 | 65 HRC | 3 % IACS |
HT 66–68 HRC | Pick for maximum red hardness and wear life on light-feed cutting of high-strength or abrasive materials, at the cost of toughness. | 2,150 | 2,400 | 0 | 67 HRC | 3 % IACS |
HT-65This page HT 64–66 HRC | General-purpose hardened condition for drills, taps, end mills and broaches with a good hardness/toughness balance. | — | 2,200 | 0.5 | 65 HRC | 24 W/m·K |
What is M34 HT-65?
M34 HT-65 is M34 heat treated to HT-65 — general-purpose hardened condition for drills, taps, end mills and broaches with a good hardness/toughness balance. M34 HT-65 has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 73% of steel grades. Elongation at break is 0.5% and the elastic modulus is 225 GPa (32.6 Msi). M34 HT-65 has a density of 8.03 g/cm³ (0.29 lb/in³), heavier than 96% of steel grades. It melts at 1,240°C (2,264 °F). A is the default condition FabDigit quotes; HT-65 is available on request or by drawing note.
Advantages
- High service temperature — 600°C (1,112 °F), better than 98% 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
- High embodied carbon — 5.6 kg CO₂/kg, worse than 98% of steel grades
- Limited formability — 10/100, worse than 95% of steel grades
- Difficult to weld — 15/100, worse than 91% of steel grades
M34 HT-65 properties
Typical room-temperature values for M34 HT-65; 15 are specific to this condition. Other listed values are M34 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
M34 HT-65 has a density of 8.03 g/cm³ (0.29 lb/in³), heavier than 96% of steel grades. It melts at 1,240°C (2,264 °F).
Mechanical14
M34 HT-65 has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 73% of steel grades. Elongation at break is 0.5% and the elastic modulus is 225 GPa (32.6 Msi).
Thermal6
M34 HT-65 is rated for continuous service to 600°C (1,112 °F). It conducts heat at 24 W/m·K (13.9 BTU/hr·ft·°F), worse than 90% of steel grades. Thermal expansion is 10.7 µm/m·K (5.94 µin/in·°F).
Electrical3
M34 HT-65 conducts electricity at 3.2 % IACS, worse than 87% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of M34 HT-65 takes about 78 MJ of energy and emits 5.6 kg of CO₂ — more than 98% of steel grades. Typical recycled content is 40%.
Manufacturability8
M34 HT-65's machinability is not recommended (8/100, worse than 100% of steel grades); weldability poor (15/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with M34 HT-65
Is M34 easy to machine?
Machine only in the annealed condition with sharp carbide or coated-carbide tooling, rigid setups and generous coolant; hardened parts require grinding or EDM with CBN/vitrified alumina wheels.
Can M34 be welded?
Fusion welding is avoided except for tool repair (TIG with matching HSS filler at 500–550 °C preheat plus immediate re-temper); shank-to-flute joints are normally friction- or flash-welded.
Can M34 be formed, bent or molded?
Hot work only, forging 1050–1150 °C finishing above 900 °C followed by slow cooling and full anneal; essentially no cold formability.
What surface finishes work on M34?
Not anodizable — protect with steam oxide, black oxide, phosphate or oil; nitriding and PVD TiN/TiAlN coatings applied below the tempering temperature give the best tool life.
M34 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 | 0.85 – 0.92 | 0.89 |
| Mn | 0.15 – 0.4 | 0.3 |
| Si | 0.2 – 0.45 | 0.3 |
| Cr | 3.5 – 4 | 3.75 |
| Mo | 7.75 – 9.2 | 8.3 |
| W | 1.4 – 2.1 | 1.9 |
| V | 1.9 – 2.3 | 2.05 |
| Cored-hardness addition | 7.75 – 8.75 | 8.25 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
M34 HT-65 — frequently asked
What is M34 HT-65 used for?
M34 HT-65 is typically used for cutting tools for tough alloys, milling cutters and drills for high-temp alloys. In short: 550 °C service rating; cobalt toughness balance; for high-temp alloy cutting.
What is the yield strength of M34 HT-65?
M34 HT-65 has a typical yield strength of 560 MPa (81.2 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 73% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is M34 HT-65 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 sharp carbide or coated-carbide tooling, rigid setups and generous coolant; hardened parts require grinding or EDM with CBN/vitrified alumina wheels.
Can M34 HT-65 be welded?
Not readily — weldability is rated poor (15/100). Fusion welding is avoided except for tool repair (TIG with matching HSS filler at 500–550 °C preheat plus immediate re-temper); shank-to-flute joints are normally friction- or flash-welded.
What surface finishes work on M34 HT-65?
Not anodizable — protect with steam oxide, black oxide, phosphate or oil; nitriding and PVD TiN/TiAlN coatings applied below the tempering temperature give the best tool life.
Can M34 HT-65 be formed, bent or molded?
Hot work only, forging 1050–1150 °C finishing above 900 °C followed by slow cooling and full anneal; essentially no cold formability.
What is the maximum service temperature of M34 HT-65?
M34 HT-65 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 M34-A and M34 HT-67?
A is the default condition — standard supply condition for machining tool blanks before hardening. HT-67: pick for maximum red hardness and wear life on light-feed cutting of high-strength or abrasive materials, at the cost of toughness. Yield strength is 560 MPa in A versus 2,150 MPa in HT-67.
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)
- Cobalt molybdenum high-speed steel product data (M-series) — 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.