What each standard covers
ASTM B209 is the American specification for aluminium and aluminium-alloy sheet and plate. It is the default in North American drawings and it is widely accepted elsewhere. EN 485 is the European series covering wrought aluminium sheet, strip and plate; it is published in parts covering technical conditions, mechanical properties and dimensional tolerances. GB/T 3880 is the Chinese national standard for aluminium alloy plate, sheet and strip for general engineering, also in parts. JIS H4000 is the Japanese counterpart, commonly cited in Japanese supply chains.
All four describe chemistry, mechanical properties and dimensional tolerances for the same physical product. They are not describing different metal; they are describing it with different tables.
Where they actually differ
- Tolerance values. The permitted thickness deviation at a given width and thickness is not identical across standards, and the difference is real at tight tolerances.
- Temper notation. EN uses designations such as H111 and H112 that have no direct ASTM equivalent. Mapping them loosely is a common source of disputes.
- Test method references. Tensile testing, bend testing and corrosion testing are referenced to different method standards, which can produce slightly different results on the same material.
- Scope and exclusions. Some standards exclude certain alloys, tempers or thickness bands; assuming coverage before checking is a mistake that costs time.
- Units and rounding. Metric versus imperial tables produce rounding differences that matter when a tolerance is expressed to two decimal places.
What to do when they conflict
Decide which standard governs, and say so on the order. The cleanest wording names one standard for properties and tolerances and adds any additional requirement explicitly, rather than citing two standards and leaving the precedence unstated.
Where a buyer's drawing cites ASTM but the item will be produced in China, the practical question is whether the mill can hold the ASTM table. Often it can, sometimes it takes a tighter production route, and occasionally it takes a different mill. That is a question for the enquiry stage, because after production it is an argument.
If you send us the drawing, we will say which standard the quoted mill works to and whether the cited table can be held — before you commit, not on the inspection report.
Comparison table
| Standard | Origin | Typical citation |
|---|---|---|
| ASTM B209 | United States | North American drawings; widely accepted globally |
| EN 485 | Europe | European projects and EN-based specifications |
| GB/T 3880 | China | Chinese domestic engineering and many export orders |
| JIS H4000 | Japan | Japanese supply chains and Japanese-owned plants |
Name one governing standard and tell us if a second one appears anywhere in the drawing package. We would rather resolve the precedence in writing than discover it when the gauge is measured.