SIST EN 3335:2005

SIST EN 3335:2005 is the Slovenian standard identical to EN 3335:2005 for aerospace aluminium sheet. It specifies the requirements for aluminium alloy AL-P7475-O2 sheet for superplastic forming (SPF) in the thickness range 0.8 mm to 6 mm, for aerospace application. Manufacturers, purchasers and test laboratories use it to agree the product form, heat treatment, testing and acceptance criteria.

What does SIST EN 3335:2005 specify?

SIST EN 3335:2005 is a product standard for a specific aluminium alloy sheet used in aerospace SPF applications. Clause 1 gives the scope, clause 2 lists the normative references, and the main body is a requirement table that covers the material, processing, tests and inspection.

The standard applies to sheet in the designated alloy and thickness range only. In practice, that means buyers and suppliers can use one document to define what material is being ordered and how it will be checked on delivery.

What are the key requirements of SIST EN 3335:2005?

Composition and product form

SIST EN 3335:2005 identifies the material as aluminium alloy AL-P7475-O2 in sheet form, produced by rolling and thermomechanical processing to improve SPF capability. The chemical composition table sets limits for the alloying elements and impurity elements, with aluminium as the base metal.

This matters because the chemistry and processing route control formability, strength and consistency from batch to batch. For procurement and incoming inspection, the document is the basis for verifying that the supplied sheet matches the specified alloy and condition.

Delivery condition, heat treatment and mechanical properties

SIST EN 3335:2005 requires delivery in condition O2 and gives a reference heat treatment for the release test condition T762. It also states that the heat treatment and minimum properties are for manufacturer release testing and may not necessarily be achieved in superplastically formed parts.

The requirement table sets minimum proof stress, tensile strength and elongation at ambient temperature in both the L and LT directions. In practice, this tells the manufacturer which test directions to use and which properties must be demonstrated before the batch is accepted.

Sampling, conductivity, grain size and defects

SIST EN 3335:2005 refers to EN 4400-2 for test samples, test pieces, grain size, external defects, marking inspection and dimensional inspection. It also gives a conductivity check after the T762 heat treatment, with acceptance linked to both conductivity and proof stress.

For the user, this means the batch is not judged only by chemistry and strength - it also has to meet microstructural and surface-condition requirements. That is important when sheet will later be formed into safety-critical aerospace components.

Superplastic forming capability and handling notes

SIST EN 3335:2005 includes a dedicated superplastic forming capability requirement. The capability is assessed by an elevated-temperature tensile test on samples taken per direction per batch, and the standard sets the acceptance criterion for elongation.

The notes also state that cold working or straightening is only acceptable within the stated strain limit. In practice, this protects the SPF behaviour of the sheet and helps preserve the properties needed for forming.

What terms does SIST EN 3335:2005 define?

• AL-P7475-O2 - the designated aluminium alloy and delivery condition covered by the standard.
• SPF - superplastic forming, the process the sheet is intended for.
• O2 - the delivery condition required for supplied sheet.
• T762 - the reference heat treatment used for release testing.
• WQ - water quench, part of the reference heat treatment route.
• Capability clause - the agreed provision that can reduce sampling when the manufacturer and purchaser accept it.

Who uses SIST EN 3335:2005?

SIST EN 3335:2005 is used by aerospace material suppliers, sheet manufacturers, purchasers, quality managers and test laboratories. They use it to specify the product, qualify batches, run acceptance tests, check dimensional and marking inspection, and decide whether the sheet is suitable for SPF parts.

It is also relevant for organizations that need to agree a common material basis before forming components. That makes ordering, release testing and incoming inspection easier to align across supply chains.

Which standards are used with SIST EN 3335:2005?

• EN 4258 - gives the general organization of aerospace metallic material standards and the links between EN standard types and their use.
• EN 4400-2 - gives the technical specification for aluminium and aluminium alloy wrought products, sheet and strip, and is used here for sampling, testing and several inspection items.
• EN 4500-2 - gives the rules for drafting and presentation of material standards for aluminium, aluminium alloys and magnesium alloys.

What does the SIST EN 3335:2005 document contain?

The document contains a specification table that covers material designation, chemical composition, method of melting, product form, production method, dimensional range, technical specification, delivery condition, test directions and temperature. It also sets out the required mechanical properties and additional checks such as conductivity, grain size, external defects and dimensional inspection.

Another part of the table describes the superplastic forming capability test, including the elevated-temperature tensile test setup used to assess elongation. The notes section adds guidance on sampling, acceptable handling after processing and how the properties relate to release testing.