Steel F1 · heat-treated state
Steel F1 HT-64
Properties of the HT-64 condition, compared with the other F1 tempers.
Maximum hardness and wear resistance for paper/leather knives, engraving tools and light blanking punches; minimum toughness.
What is F1 HT-64?
F1 HT-64 is F1 heat treated to HT-64 — maximum hardness and wear resistance for paper/leather knives, engraving tools and light blanking punches; minimum toughness. F1 HT-64 has a yield strength of 1,900 MPa (276 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 100% of steel grades. Elongation at break is 1% and the elastic modulus is 205 GPa (29.7 Msi). F1 HT-64 has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F). ANN is the default condition FabDigit quotes; HT-64 is available on request or by drawing note.
Advantages
- High strength — 1,900 MPa (276 ksi), better than 100% of steel grades
- Polishes to a fine finish — 85/100, better than 99% of steel grades
Limitations
- Limited ductility — 1%, worse than 100% of steel grades
- Difficult to machine — 8/100, worse than 100% of steel grades
- Difficult to weld — 5/100, worse than 100% of steel grades
- Limited formability — 2/100, worse than 100% of steel grades
- Limited service temperature — 150°C (302 °F), worse than 99% of steel grades
F1 HT-64 properties
Typical room-temperature values for F1 HT-64 — 19 properties are specific to this condition; the rest are grade-level values shared by every F1 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
F1 HT-64 has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical15
F1 HT-64 has a yield strength of 1,900 MPa (276 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 100% of steel grades. Elongation at break is 1% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
F1 HT-64 is rated for continuous service to 150°C (302 °F). It conducts heat at 38 W/m·K (22 BTU/hr·ft·°F), worse than 68% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
F1 HT-64 conducts electricity at 9.5 % IACS, better than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 87% of steel grades.
Sustainability4
Producing a kilogram of F1 HT-64 takes about 33 MJ of energy and emits 2.3 kg of CO₂ — more than 76% of steel grades. Typical recycled content is 30%.
Manufacturability8
F1 HT-64's machinability is not recommended (8/100, worse than 100% of steel grades); weldability not recommended (5/100); formability not recommended (2/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other F1 tempers and conditions
F1 is also supplied in 6 other conditions. The full side-by-side table is on the F1 overview.
- ANNDefaultStandard stock condition for machining, sawing and shaping tool blanks before water hardening.420 MPa yield · 197 HB
- HT-64Maximum hardness and wear resistance for paper/leather knives, engraving tools and light blanking punches; minimum toughness.1,900 MPa yield · 63 HRC
- HT-60Balanced hardening condition for punches, dies, woodworking cutters and taps needing some shock resistance.1,750 MPa yield · 60 HRC
- HT-56Highest-toughness hardened condition for shock-loaded light tooling; upper practical tempering limit for this grade.1,600 MPa yield · 57 HRC
- CD-ANNPick for close-tolerance, bright-finish small bar used for taps, punches and pins with minimal pre-machining.600 MPa yield · 217 HB
Working with F1 HT-64
Is F1 easy to machine?
Machine only in the spheroidize-annealed condition (~75 % of AISI 1212) with sharp HSS/carbide and steady feeds; after water hardening it must be ground with soft, free-cutting wheels and ample coolant to avoid grinding cracks.
Can F1 be welded?
Essentially non-weldable for structural joints; repair only with preheat 300–400 °C, matched high-carbon filler, immediate stress relief and re-hardening — cracking and soft zones are otherwise certain.
Can F1 be formed, bent or molded?
Hot forge 1010→860 °C then slow cool and spheroidize anneal at 760–790 °C; cold forming limited to mild bending of annealed strip. Harden from 790–845 °C with brine/water quench (allow ~1.5–4 mm case) and temper immediately at 150–260 °C — never above 260 °C.
What surface finishes work on F1?
Takes a fine polish for cutting edges; provide corrosion protection by oiling, black oxide, phosphate or thin hard chrome — no anodizing, and any plating bake-out must stay below the tempering temperature.
F1 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 A686 F1 | 0.95 – 1.25 | 1 |
| Mn | 0.1 – 0.4 | 0.25 |
| Si | 0.1 – 0.4 | 0.25 |
| Wprincipal carbide former for wear resistance | 1 – 1.75 | 1.25 |
| Croptional/residual | ≤ 0.3 | 0.15 |
| Voptional/residual | ≤ 0.25 | — |
| Moresidual | ≤ 0.25 | — |
| Niresidual | ≤ 0.3 | — |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
F1 HT-64 — frequently asked
What is F1 HT-64 used for?
F1 HT-64 is typically used for taps, reamers, light punches, small dies and hand tools. In short: water-hardening tungsten grade; shallow case, tough core; best machinability of family.
What is the yield strength of F1 HT-64?
F1 HT-64 has a typical yield strength of 1,900 MPa (276 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 100% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is F1 HT-64 easy to machine?
Not especially — machinability is rated not recommended (8/100, worse than 100% of steel grades). Machine only in the spheroidize-annealed condition (~75 % of AISI 1212) with sharp HSS/carbide and steady feeds; after water hardening it must be ground with soft, free-cutting wheels and ample coolant to avoid grinding cracks.
Can F1 HT-64 be welded?
Not readily — weldability is rated not recommended (5/100). Essentially non-weldable for structural joints; repair only with preheat 300–400 °C, matched high-carbon filler, immediate stress relief and re-hardening — cracking and soft zones are otherwise certain.
What surface finishes work on F1 HT-64?
Takes a fine polish for cutting edges; provide corrosion protection by oiling, black oxide, phosphate or thin hard chrome — no anodizing, and any plating bake-out must stay below the tempering temperature.
Can F1 HT-64 be formed, bent or molded?
Hot forge 1010→860 °C then slow cool and spheroidize anneal at 760–790 °C; cold forming limited to mild bending of annealed strip. Harden from 790–845 °C with brine/water quench (allow ~1.5–4 mm case) and temper immediately at 150–260 °C — never above 260 °C.
What is the maximum service temperature of F1 HT-64?
F1 HT-64 is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between F1-ANN and F1 HT-64?
ANN is the default condition — standard stock condition for machining, sawing and shaping tool blanks before water hardening. HT-64: maximum hardness and wear resistance for paper/leather knives, engraving tools and light blanking punches; minimum toughness. Yield strength is 420 MPa in ANN versus 1,900 MPa in HT-64.
Sources
- ASTM A686 — Standard Specification for Carbon Tool Steels — ASTM International (2019)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys (Tool Steels) — ASM International (1990)
- Tool Steels, 5th ed. (Roberts, Krauss, Kennedy) — ASM International (1998)
- ASM Handbook Vol.16: Machining — ASM International (1989)
- SAE J437/J438 — Tool and Die Steels — SAE International (2015)
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.