About Smiths

We are a world-class supplier of engineering raw materials. Our objective is to provide all our customers, from the small machine shop to the large multi-national corporation, a supply path that continuously delivers the highest levels of service, quality and value.

5251 Aluminium Alloy

Commercial Aluminium

5251 (NS4) Commercial Aluminium Alloy

5251 (NS4) - an alloyed non-heat-treatable rolled aluminium sheet designed for general sheet metal work where higher mechanical properties are required together with a degree of formability.


Internationally recognised grade EN AW 5251 H22 – AlMg2 hardened to the quarter-hard temper is formerly known as NS4 H3 under the British Standard specification. Our product meets all appropriate national and international standards.


The higher strength and extra hardness of grade 5251 over pure aluminium give improved machinability properties. Machinability of the alloy is reasonable, though not as good when compared to the machining of heat-treated alloys. The alloy finds suitability in applications, including marine environments.

During general fabrication, we recommend aluminium geometry cutting tools running at a reasonable speed to avoid the edge build-up, which can occur at lower cutting speeds. High-speed steel tools may be more economical than carbide, particularly with the possibility of a large rake angle on machines which cannot reach carbide cutting speeds.

Typical Applications

Commercial applications for this engineering material include:

  • Boiler making
  • Heat transfer devices
  • Offshore
  • Pressure vessels
  • Panelling
  • Welded structures
  • Metalwork

We stock 5251 in round bar, plate, sheet, strip, round tube and hollow bar.

Technical Assistance

Our knowledgeable staff and resident metallurgists will be pleased to assist you further on any technical topic. Smiths Metal Centres Limited also boasts an in-house UKAS Accredited Testing Laboratory which is unique within the multi-metal and plastic stockholding sector. We believe this underlines our total commitment to quality and our ethos of being the complete service provider.

Additional Info

A technical datasheet for 5251 is available in PDF file format. To view and download, please click here.

We offer in-house processing options - for more information, please refer to our processing services.

Read our corporate brochure by clicking here.

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