Why the Choice Between 1050, 1060 and 1070 Matters
All three grades are commercially pure aluminium from the 1xxx series, where the alloy number states the minimum aluminium content: 99.50 percent for 1050, 99.60 percent for 1060 and 99.70 percent for 1070. None of them responds to heat treatment, so their properties are developed by cold working and annealing rather than by solution treatment and ageing. In ordinary service the three grades behave almost identically, which is why the difference only becomes important when a specification, a customer drawing or a conductivity requirement turns purity into a contractual point.
Grade Designations and Purity Limits
| Grade | Minimum aluminium | European designation | Chinese designation |
|---|---|---|---|
| 1050 | 99.50 percent | EN AW-1050A | 1050A |
| 1060 | 99.60 percent | EN AW-1060 | 1060 |
| 1070 | 99.70 percent | EN AW-1070A | 1070A |
The balance of each grade is made up of iron, silicon, copper and other residual elements. The 1070 grade also permits a small vanadium addition of up to 0.05 percent, which refines the grain and raises the recrystallisation temperature, giving a more uniform microstructure after fabrication. Designations follow EN 573-3 and GB/T 3190, so a European enquiry for EN AW-1060 and a Chinese order for 1060 refer to the same material.
Mechanical Behaviour and Temper Designations
Tube and pipe in these grades are ordered in the annealed O temper or in strain-hardened tempers such as H12, H14 and H18, using the temper designations of EN 515 and ANSI H35.1. Cold drawing raises strength and lowers elongation, while annealing restores ductility and electrical conductivity. Because the three grades share the same face-centred cubic structure, their strength at a given temper is very similar and their elongation remains good, which is why they bend, flare and coil without difficulty.
The property that genuinely separates them is conductivity. Electrical and thermal conductivity rise with aluminium content, so 1070 is the best conductor of the three, followed by 1060 and then 1050. Where a conductor or heat-exchanger duty specifies a conductivity figure, the grade should be selected on that basis rather than on availability alone.
Applicable Standards
ASTM B210 covers drawn seamless aluminium tube for general service, ASTM B234 covers drawn seamless tube for condensers and heat exchangers, and ASTM B241 covers extruded tube and pipe in the commercially pure grades. In Europe, EN 754-2 gives mechanical property requirements for drawn tube, EN 755-2 covers extruded tube and profiles, EN 755-8 covers the dimensional tolerances of extruded tube, and EN 573-3 defines the chemical composition. A complete order therefore names the grade, the temper, the product standard and the size.
Typical Applications
Heat exchanger and condenser tubes in power stations and process plants
Electrical conductors, busbar enclosures and instrument tubing
Refrigeration and air-conditioning coils and capillary tube
Food, dairy and pharmaceutical process lines that require a non-toxic, corrosion-resistant surface
Architectural trim and decorative tube in mill or anodised finish
Where a project needs both formability and electrical performance, the designer should check which of the two requirements is tighter. Many specifications simply call for a commercial purity grade and a temper, in which case 1050 in the required temper satisfies the duty at the lowest cost.
How to Specify and Process the Correct Grade
Start from the requirement that actually matters. If a minimum aluminium content or a conductivity figure is stated, select the grade that meets it and record the temper on the drawing. If only formability and corrosion resistance matter, 1050 is normally sufficient and is the most economical choice in an equivalent temper. A clear specification gives grade, temper, standard, outside diameter, wall thickness and length, and states whether pressure testing or eddy current examination is required.
Aluminium tube is easy to form but soft. Bending radii should follow the recommendations of the applicable standard, mandrel bending avoids flattening on thin walls, and tooling must be kept clean and free of steel particles to prevent surface contamination. Annealing between cold-forming steps restores ductility, and welding should use procedures qualified for the specific thickness and joint design. All three grades resist corrosion well in neutral atmospheres, but they are attacked by strong alkalis, and direct contact with copper, steel or stainless steel in a wet environment should be avoided to prevent galvanic corrosion.
FAQ
Q: Are 1050, 1060 and 1070 heat treatable?
No. They are non-heat-treatable 1xxx series grades, so strength is controlled by cold work and annealing rather than by thermal treatment alone.
Q: Which grade has the highest conductivity?
1070 has the highest minimum purity and therefore the highest electrical and thermal conductivity, followed by 1060 and then 1050.
Q: Which grade should I choose for general service?
1050 in the required temper is usually adequate, because the practical difference in mechanical behaviour between the three grades is small.
Q: Can the three grades be welded?
Yes, all three weld readily by gas tungsten arc and related processes, although strength in the weld zone is reduced and the joint design should account for that.
Q: What is the difference between EN AW-1070A and 1070?
The letters identify the European registration system and the additional letter marks a controlled impurity variant of the same base grade.
Q: How is the tube supplied?
Drawn seamless tube in straight lengths or coils, in the annealed or strain-hardened temper requested, with the temper, size and heat number marked on each bundle.
