Two Pure Aluminium Grades Compared
1050 and 1350 aluminium coil look identical on the warehouse floor, and both are produced from commercially pure aluminium with a minimum aluminium content of 99.5%. The difference lies in how tightly the residual elements are controlled, and that difference decides which applications each grade can serve. 1050 is the general purpose pure aluminium grade found in heat sinks, nameplates, cookware and decorative trim. 1350 is a conductor grade in which the residuals that depress electrical conductivity are deliberately restricted.
Because both grades are non-heat-treatable, their strength depends only on the amount of cold work applied. Neither can be strengthened by thermal treatment, so the temper designation, not the alloy number, is what determines the mechanical properties of the delivered coil.
Composition and Standard Coverage
| Item | 1050 aluminium coil | 1350 aluminium coil |
|---|---|---|
| Aluminium content | 99.50% minimum | 99.50% minimum |
| Main residual elements | Iron and silicon, small amounts | Iron and silicon, with tightened limits |
| Chromium | Not specially controlled | 0.01% maximum |
| Vanadium and titanium | Not specially controlled | Restricted to protect conductivity |
| Product standards | ASTM B209, EN 573-3, GB/T 3880 | ASTM B209, ASTM B230 for wire, EN 573-3 |
The chromium, vanadium and titanium limits in 1350 exist for one purpose: these elements reduce electrical conductivity sharply even at very low concentrations. Restricting them is what allows 1350 to hold a minimum conductivity around 61% of the international annealed copper standard, a level the general purpose 1050 grade is not required to guarantee.
Electrical and Thermal Conductivity
Aluminium's high conductivity per unit weight is the reason both grades are selected for electrical and thermal duty. On a mass basis aluminium carries roughly twice the current of copper for the same conductor weight, which is why it dominates overhead transmission and large busbar installations. 1350 is the preferred grade where conductivity is the governing requirement; 1050 remains adequate for heat sinks, heat exchangers and general electrical hardware where the duty is thermal rather than high-current electrical.
Strength, Formability and Temper Selection
| Characteristic | 1050 aluminium | 1350 aluminium |
|---|---|---|
| Strength level | Low; cannot be heat treated | Low; cannot be heat treated |
| Strengthening method | Cold work only | Cold work only |
| Formability | Excellent, very ductile | Excellent, very ductile |
| Typical temper | O, H14, H16, H18, H22, H24 | O, H14, H16, H18, H22, H24 |
| Typical conductivity use | Heat sinks and general electrical parts | Wires, cables, busbars and transformer strip |
Because both alloys are soft in the annealed condition and gain strength only through rolling, the O temper is used for deep drawing and severe forming, while H14 to H18 tempers are chosen for stiffness in flat parts. The trade-off is always the same: harder temper, higher strength, lower elongation.
Typical Applications and Selection Advice
1050: heat sinks, heat exchanger fins, nameplates, signage, lighting reflectors, cookware, decorative trim
1050: chemical and food processing equipment where purity matters
1350: electrical busbars, transformer strip and cable wrap
1350: conductor applications where minimum conductivity is a contractual requirement
1350: high-current connections and electrical hardware
Selection is rapid if the governing requirement is identified first. If the part must carry current efficiently, choose 1350 and specify the conductivity requirement on the purchase order. If the part must conduct or dissipate heat, form easily and look clean, 1050 is normally sufficient and less expensive. Deep-drawn parts of either grade should be ordered in a soft temper, and any requirement for surface finish, width tolerance or coil inner diameter should be stated explicitly, since these details vary between producers and affect downstream yield.
Frequently Asked Questions
Q: Are 1050 and 1350 the same alloy?
A: No. Both are commercially pure grades with at least 99.5% aluminium, but 1350 imposes much tighter limits on chromium, vanadium and titanium so that electrical conductivity can be guaranteed.
Q: Which grade has better conductivity?
A: 1350. Its controlled residual content allows a minimum conductivity of about 61% of the international annealed copper standard, which 1050 is not required to guarantee.
Q: Can either grade be heat treated?
A: No. Both are non-heat-treatable, so strength is obtained only by cold work. Tempers such as H14, H16, H18 and H24 define the delivered mechanical condition.
Q: Which one is better for a heat sink?
A: 1050 is normally adequate and more economical. Thermal conductivity of the two grades is very similar; the tighter conductivity control of 1350 matters mainly for high-current electrical duty.
Q: What tempers are commonly stocked?
A: O, H14, H16, H18, H22 and H24 are the usual tempers, with the choice driven by the forming operation and the stiffness required in service.
Q: Are the coils supplied to an international standard?
A: Sheet and coil are normally ordered to ASTM B209 or the equivalent clauses of EN 573-3 and GB/T 3880, with 1350 wire also covered by ASTM B230.
