Steel M46-HT64
Heat-treated state
AISI/SAE M46 · UNS T11346
HT64 = hardened & tempered
Lower the hardening temperature or raise the tempering temperature to 64–66 HRC when interrupted cutting, cold-heading punches and impact-loaded forming tools need edge-chipping resistance.
Values for the HT64 condition
Other M46 tempers and conditions
M46 is listed in 3 conditions; see the grade overview at M46.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefault Annealed | Order the spheroidize annealed bar or blank at ≤269 HB for turning, milling, drilling and forming, then harden and temper afterwards to reach service hardness. | 560 | 850 | 12 | 255 HB | 24 W/m·K |
Hardened & triple tempered | Choose salt-bath or vacuum hardening at 1190–1210 °C with three tempers at 540–550 °C to 67–69 HRC for drills, taps and cutters on hard materials where wear resistance outweighs toughness. | 1,900 | 2,100 | 0.5 | 68 HRC | 21 W/m·K |
HT64This page Hardened & tempered | Lower the hardening temperature or raise the tempering temperature to 64–66 HRC when interrupted cutting, cold-heading punches and impact-loaded forming tools need edge-chipping resistance. | — | 2,300 | — | 65 HRC | — |
What is M46-HT64?
M46-HT64 is M46 heat treated to HT64 — lower the hardening temperature or raise the tempering temperature to 64–66 HRC when interrupted cutting, cold-heading punches and impact-loaded forming tools need edge-chipping resistance. M46-HT64 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 12% and the elastic modulus is 228 GPa (33.1 Msi). M46-HT64 has a density of 8 g/cm³ (0.289 lb/in³), heavier than 95% of steel grades. It melts at 1,270°C (2,318 °F). ANN is the default condition FabDigit quotes; HT64 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
- Difficult to machine — 6/100, worse than 100% of steel grades
- High embodied carbon — 4.2 kg CO₂/kg, worse than 95% of steel grades
- Difficult to weld — 15/100, worse than 91% of steel grades
- Poor heat conductor — 24 W/m·K (13.9 BTU/hr·ft·°F), worse than 90% of steel grades
- Low electrical conductivity — 3.1 % IACS, worse than 89% of steel grades
M46-HT64 properties
Typical room-temperature values for M46-HT64; 12 are specific to this condition. Other listed values are M46 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
M46-HT64 has a density of 8 g/cm³ (0.289 lb/in³), heavier than 95% of steel grades. It melts at 1,270°C (2,318 °F).
Mechanical15
M46-HT64 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 12% and the elastic modulus is 228 GPa (33.1 Msi).
Thermal6
M46-HT64 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 10.8 µm/m·K (6 µin/in·°F).
Electrical3
M46-HT64 conducts electricity at 3.1 % IACS, worse than 89% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of M46-HT64 takes about 55 MJ of energy and emits 4.2 kg of CO₂ — more than 94% of steel grades. Typical recycled content is 30%.
Manufacturability8
M46-HT64's machinability is not recommended (6/100, worse than 100% of steel grades); weldability poor (15/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with M46-HT64
Is M46 easy to machine?
Machine only in the annealed condition (≤269 HB) using cobalt-HSS or coated carbide tooling, low speed with heavier feed and full coolant. Once hardened, only grinding (CBN wheels preferred) or EDM is practical.
Can M46 be welded?
Normally not welded. Where repair is unavoidable, TIG build-up with a matching high-cobalt HSS filler at 450–550 °C preheat, followed immediately by a stress-relief temper.
Can M46 be formed, bent or molded?
In the annealed state it can be hot forged starting at 1050–1150 °C and finishing no lower than 900 °C, then slow cooled and annealed. Cold formability is very poor.
What surface finishes work on M46?
After hardening and tempering, grind and polish; typical surface treatments are steam blackening, oxide treatment or TiN/TiAlN PVD coating. It cannot be anodized, and stock should be oiled to prevent rust.
M46 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 | 1.22 – 1.3 | 1.26 |
| Mn | 0.2 – 0.4 | 0.3 |
| Si | 0.4 – 0.65 | 0.5 |
| Cr | 3.7 – 4.2 | 3.95 |
| Mo | 8 – 8.5 | 8.25 |
| W | 1.9 – 2.2 | 2.05 |
| V | 3 – 3.3 | 3.15 |
| Co | 7.8 – 8.8 | 8.25 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
M46-HT64 — frequently asked
What is M46-HT64 used for?
M46-HT64 is typically used for punches and dies, milling cutters, taps and reamers. In short: balanced hardness and toughness; cobalt HSS for impact tooling; coatable to 67 HRC.
What is the yield strength of M46-HT64?
M46-HT64 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 3 listed tempers.
Is M46-HT64 easy to machine?
Not especially — machinability is rated not recommended (6/100, worse than 100% of steel grades). Machine only in the annealed condition (≤269 HB) using cobalt-HSS or coated carbide tooling, low speed with heavier feed and full coolant. Once hardened, only grinding (CBN wheels preferred) or EDM is practical.
Can M46-HT64 be welded?
Not readily — weldability is rated poor (15/100). Normally not welded. Where repair is unavoidable, TIG build-up with a matching high-cobalt HSS filler at 450–550 °C preheat, followed immediately by a stress-relief temper.
What surface finishes work on M46-HT64?
After hardening and tempering, grind and polish; typical surface treatments are steam blackening, oxide treatment or TiN/TiAlN PVD coating. It cannot be anodized, and stock should be oiled to prevent rust.
Can M46-HT64 be formed, bent or molded?
In the annealed state it can be hot forged starting at 1050–1150 °C and finishing no lower than 900 °C, then slow cooled and annealed. Cold formability is very poor.
What is the maximum service temperature of M46-HT64?
M46-HT64 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 M46-ANN and M46-HT67?
ANN is the default condition — order the spheroidize annealed bar or blank at ≤269 HB for turning, milling, drilling and forming, then harden and temper afterwards to reach service hardness. HT67: choose salt-bath or vacuum hardening at 1190–1210 °C with three tempers at 540–550 °C to 67–69 HRC for drills, taps and cutters on hard materials where wear resistance outweighs toughness. Yield strength is 560 MPa in ANN versus 1,900 MPa in HT67.
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 Specialty Handbook: Tool Materials — ASM International (1995)
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.