Aluminum Hokotol · temper
Aluminum Hokotol-T651
Properties of the T651 condition, compared with the other Hokotol tempers.
Choose when maximum strength and hardness are required and the part will not see humid/chloride SCC service.
What is Hokotol-T651?
Hokotol-T651 is Hokotol in the T651 temper — choose when maximum strength and hardness are required and the part will not see humid/chloride SCC service. Hokotol-T651 has a yield strength of 505 MPa (73.2 ksi) and a tensile strength of 565 MPa (81.9 ksi) — stronger than 96% of aluminum grades. Elongation at break is 5% and the elastic modulus is 71 GPa (10.3 Msi). Hokotol-T651 has a density of 2.82 g/cm³ (0.102 lb/in³), heavier than 89% of aluminum grades. It melts at 477°C (891 °F).
Advantages
- High strength — 505 MPa (73.2 ksi), better than 96% of aluminum grades
- Easy to machine — 84/100, better than 94% of aluminum grades
- Polishes to a fine finish — 75/100, better than 90% of aluminum grades
Limitations
- Difficult to weld — 18/100, worse than 94% of aluminum grades
- Limited service temperature — 100°C (212 °F), worse than 91% of aluminum grades
- Needs corrosion protection — 34/100, worse than 88% of aluminum grades
Hokotol-T651 properties
Typical room-temperature values for Hokotol-T651 — 11 properties are specific to this condition; the rest are grade-level values shared by every Hokotol temper. Each bar shows where the value sits among the aluminum grades in FabDigit's library — further right is higher.
Physical3
Hokotol-T651 has a density of 2.82 g/cm³ (0.102 lb/in³), heavier than 89% of aluminum grades. It melts at 477°C (891 °F).
Mechanical12
Hokotol-T651 has a yield strength of 505 MPa (73.2 ksi) and a tensile strength of 565 MPa (81.9 ksi) — stronger than 96% of aluminum grades. Elongation at break is 5% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
Hokotol-T651 is rated for continuous service to 100°C (212 °F). It conducts heat at 130 W/m·K (75.1 BTU/hr·ft·°F), worse than 65% of aluminum grades. Thermal expansion is 23.4 µm/m·K (13 µin/in·°F).
Electrical3
Hokotol-T651 conducts electricity at 33 % IACS, worse than 57% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is poor (34/100), worse than 88% of aluminum grades.
Sustainability4
Producing a kilogram of Hokotol-T651 takes about 155 MJ of energy and emits 12 kg of CO₂ — less than 94% of aluminum grades. Typical recycled content is 25%.
Manufacturability7
Hokotol-T651's machinability is very good (84/100, better than 94% of aluminum grades); weldability poor (18/100); formability poor (18/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other Hokotol tempers and conditions
Hokotol is also supplied in 3 other conditions. The full side-by-side table is on the Hokotol overview.
- T651Choose when maximum strength and hardness are required and the part will not see humid/chloride SCC service.505 MPa yield · 172 HB
- T7651Compromise temper: near-T6 strength with markedly better exfoliation/SCC behaviour than peak-aged plate.485 MPa yield · 162 HB
- STDDefault stock condition for Hokotol plate: best balance of ~480 MPa yield, low residual stress and stable machining for moulds and jigs.480 MPa yield · 165 HB
- T7451Pick for thick machined tooling and structural blocks where residual stress, toughness and stress-corrosion resistance matter more than peak strength.460 MPa yield · 155 HB
Working with Hokotol-T651
Is Hokotol easy to machine?
Excellent high-speed machining with polished-flute carbide tools, large positive rake and flood or MQL cooling; low residual stress means minimal distortion when hogging deep mould cavities.
Can Hokotol be welded?
Essentially not arc-weldable (hot cracking, large strength loss in the HAZ); join mechanically or use inserts, and repair only by qualified friction-stir or specialist procedures.
Can Hokotol be formed, bent or molded?
Supplied as aged thick plate — no cold forming; shape by machining, and avoid re-solution treating locally since properties depend on the mill quench.
What surface finishes work on Hokotol?
Hard-anodize or Ni-plate mould surfaces for wear and gas resistance; clear decorative anodize looks grey, so paint or chromate-free conversion coating is preferred for humid environments.
Hokotol 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 |
|---|---|---|
| Znproprietary AlZnMgCu chemistry; range given from the 7010/7050/7075 family the alloy belongs to | 5.5 – 7 | 6.2 |
| Mg | 1.8 – 2.6 | 2.2 |
| Cu | 1.2 – 2 | 1.6 |
| Zrgrain-structure control in thick plate | 0.05 – 0.16 | 0.11 |
| Cr | 0 – 0.2 | — |
| Mn | 0 – 0.2 | — |
| Fekept low for toughness | ≤ 0.15 | — |
| Si | ≤ 0.12 | — |
| Ti | ≤ 0.06 | — |
| Al | balance | — |
Hokotol-T651 — frequently asked
What is Hokotol-T651 used for?
Hokotol-T651 is typically used for injection mould tooling, blow mould cavities and blocks, compression moulds, large machining and assembly fixtures, thermoforming and vacuum tools and aerospace machined structural blanks. In short: premium mold plate.
What is the yield strength of Hokotol-T651?
Hokotol-T651 has a typical yield strength of 505 MPa (73.2 ksi) and a tensile strength of 565 MPa (81.9 ksi) — stronger than 96% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is Hokotol-T651 easy to machine?
Yes — machinability is rated very good (84/100, better than 94% of aluminum grades). Excellent high-speed machining with polished-flute carbide tools, large positive rake and flood or MQL cooling; low residual stress means minimal distortion when hogging deep mould cavities.
Can Hokotol-T651 be welded?
Not readily — weldability is rated poor (18/100). Essentially not arc-weldable (hot cracking, large strength loss in the HAZ); join mechanically or use inserts, and repair only by qualified friction-stir or specialist procedures.
What surface finishes work on Hokotol-T651?
Hard-anodize or Ni-plate mould surfaces for wear and gas resistance; clear decorative anodize looks grey, so paint or chromate-free conversion coating is preferred for humid environments.
Can Hokotol-T651 be formed, bent or molded?
Supplied as aged thick plate — no cold forming; shape by machining, and avoid re-solution treating locally since properties depend on the mill quench.
What is the maximum service temperature of Hokotol-T651?
Hokotol-T651 is rated for continuous use to about 100°C (212 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in Hokotol-T651?
Yes — Hokotol-T651 is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- Hokotol high-strength aluminium plate product information — Aleris / Novelis Rolled Products (2019)
- ASM Handbook Vol. 2: Properties and Selection — Nonferrous Alloys (7xxx wrought alloys) — ASM International (1990)
- MMPDS-17, 7050/7010/7075 thick plate T6x and T74x design values — Battelle/FAA (2022)
- EN 485-2 / ASTM B209 — aluminium plate mechanical property requirements — CEN / ASTM (2021)
- ASM Handbook Vol. 13B — corrosion of aluminium alloys — ASM International (2005)
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.