Aluminum Alloy Cross-Reference: AA, EN, DIN, JIS, ISO Designation Equivalents

Why alloy cross-referencing matters

In a globalized market, aluminum supply chains constantly cross borders. An automotive manufacturer in Mexico may receive engineering specifications from its parent company in Germany (using DIN designations), purchase primary metal from a Canadian supplier (using AA designations), and sell finished parts to an assembler in Japan (using JIS designations). Without a reliable cross-reference table, communication between these stakeholders becomes prone to costly errors.

A common mistake in international procurement is assuming that two different designations refer to different alloys, when in reality they are equivalents. For example, the alloy known in the United States as A356.0 appears as EN AC-42100 in Europe, as AlSi7Mg0.3 in the old DIN chemical nomenclature, and as AC4C in Japan. They are the same alloy with the same composition limits, but ignorance of the equivalences can lead to rejecting perfectly suitable material or, worse, requesting duplicate quotations.

Major standards organizations

Before consulting the equivalence table, it is useful to understand the designation systems used by each organization. Each has its own naming logic, and understanding it allows you to deduce information about the alloy even without consulting a table.

AA (Aluminum Association, United States)

The AA system uses a four-digit number. For casting alloys, the format is XXX.X where the first digit indicates the primary alloying element: 1xx.x = pure aluminum (99%+), 2xx.x = copper, 3xx.x = silicon + copper/magnesium, 4xx.x = silicon. The digit after the decimal indicates the product form: 0 = castings, 1 = standard ingot, 2 = ingot with broader composition. The prefix letter (A, B, C) indicates successive modifications with tighter impurity limits. Thus, A356.0 is the first modification of 356.0 with reduced maximum iron.

EN AC (European Standard)

The European EN 1706 system uses two parallel designations: a numerical one (EN AC-XXXXX) and a chemical one (EN AC-AlSiXXX). The numerical designation follows the format EN AC-4XXXX for Al-Si casting alloys. The chemical designation directly indicates the composition: EN AC-AlSi7Mg0.3 means aluminum with 7% silicon and 0.3% magnesium. Both designations are official and equivalent; the numerical one is more practical for computer systems, while the chemical one is more intuitive for engineers.

DIN (former German standard)

Before European harmonization, Germany used the DIN 1725 system with chemical designations similar to EN but with slightly different formatting: G-AlSi7Mg (where G indicates Guss = casting). Although officially replaced by EN, DIN designations still appear on legacy drawings and specifications and in informal communication within the German industry.

JIS (Japanese Industrial Standards)

Japan uses the JIS H 5202 system for aluminum casting alloys. Designations follow the format AC followed by a number: AC4C (equivalent to A356), AC2B (equivalent to 319). The system is compact but does not offer intuitive information about composition. JIS standards align closely with ISO but maintain some alloys exclusive to the Japanese market.

ISO, NF, and UNI

ISO 3522 provides an international designation system that serves as a bridge between regional systems. France used NF standards (now replaced by EN) with designations such as A-S7G03 (where A = aluminum, S = silicon, G = magnesium, and numbers indicate percentages). Italy used UNI standards with designations such as UNI 3599. Both NF and UNI have been replaced by EN in practice but appear in legacy documentation.

Complete cross-reference table

The following table presents the closest equivalences for the 18 most commercially relevant aluminum alloys. Alloys are grouped into three categories: casting alloys, primary aluminum, and extrusion/wrought alloys.

Casting alloys

Primary aluminum (remelting ingots)

Extrusión and wrought alloys (6xxx and 1xxx series)

How to read EN AC vs. AA designations

The transition between AA and EN systems is the most common in transatlantic trade. Understanding the structure of each system allows for quick translation between them.

AA casting designation breakdown

Let us take the designation A356.0 as an example. The "A" indicates it is the first modification of the base alloy 356 (tighter impurity limits, specifically maximum iron reduced from 0.6% to 0.20%). The "3" as the first digit indicates it is a 3xx.x series alloy (Al-Si with Mg or Cu). The digits "56" are the specific identifier within the series. The ".0" indicates it is a cast product (final part), not an ingot (.1 would be standard ingot).

EN casting designation breakdown

The designation EN AC-42100 breaks down as follows: "EN" indicates European standard; "AC" means aluminium casting; "4" indicates the silicon-based series; "21" is a subgroup indicating Al-Si7Mg; and "00" indicates the base variant. The parallel chemical designation EN AC-AlSi7Mg0.3 directly indicates: aluminum with 7% silicon and 0.3% magnesium. This chemical designation is self-explanatory and preferred by many engineers.

Common pitfalls and precautions

Although equivalence tables are powerful tools, their incorrect use can generate serious quality problems. The following details the most common traps.

Equivalence does not mean identity

Two designations may be "equivalent" in the sense that they describe the same base alloy, but the exact composition limits may differ between standards. For example, the AA standard for A356 specifies Si 6.5-7.5% and Mg 0.25-0.45%, while EN AC-42100 specifies Si 6.5-7.5% and Mg 0.25-0.45% idéntically. However, the JIS standard AC4C allows a slightly broader silicon range (6.5-7.5%) but with a different iron limit (0.20% vs. 0.55% in standard AC4C vs. AC4CH with restricted iron). Always request the chemical analysis certificate and compare against the limits of the specific standard your customer specifies.

Watch out for high-purity vs. standard variants

Many alloys exist in multiple purity variants. 356.0 (Fe max 0.6%) and A356.0 (Fe max 0.20%) are chemically similar but metallurgically very different: the high-purity versión has double the elongation and much better fatigue resistance. In the EN system, the lower-purity variant may appear with the "(Fe)" suffix as in EN AC-AlSi9Cu3(Fe). In the JIS system, the high-purity variant usually carries the "H" suffix (AC4CH vs. AC4C). Ensure that all supply chain participants understand which variant is being specified.

Alloys without direct equivalents

Some modern alloys have no equivalents across all systems. AlSi10MnMg (EN AC-43500) is one example: it was developed in Europe specifically for mega casting and has no official AA, JIS, or ISO designation. Similarly, some JIS-specific alloys for the Japanese market (such as AC8A for pistons) have no exact equivalent in AA or EN standards. When working with these alloys, it is necessary to specify by chemical composition directly, not by designation.

Visual equivalence map by región

The following interactive map allows you to visualize equivalences by geographic región. Select an alloy in any system to automatically see its equivalents in all other systems.