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.

Type 431

Stainless Steel

431 Stainless Steel

Type 431 is a hardenable martensitic stainless steel alloy which combines high tensile strength and torsional strength. The material is well suited to shaft manufacture due to these characteristics.

For Marine Applications

The alloy is intended for use in applications requiring good strength and toughness combined with reasonable corrosion resistance. As the alloy offers considerable resistance to saltwater corrosion, it is used widely in marine equipment and systems. Type 431 is easily machined in the annealed state, but welding is difficult due to cracking, and it is recommended that the material is preheated to improve welding performance.


Type 431 stainless steel is a heat treatable martensitic stainless - the alloy offers high tension and torsional strength and is well suited in the manufacture of shafts. However, welding is poor, and the material cannot be easily cold worked. The alloy is utilised in a number of market sectors with typical uses including laboratory equipment, pumps, shafts and propellers.

Typical Applications

Commercial applications for this engineering material include:

  • Marine systems
  • Pump & propeller shafts
  • Outboard motor driveshafts
  • Valve stems
  • Aircraft components
  • Axles

We stock Type 431 in flats and round 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 Type 431 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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