The best grade of stainless steel is type 316LN (1.4429). It has the lowest magnetic permeability, the best stability after machining and good TIG welding characteristics. It also has good corrosion resistance particularly against Chloride compounds. This material is expensive and tubes are generally not available.
The best compromise between price, performance and availability is grade 316L (1.4404). This material has very similar properties to 316LN. Good welding characteristics, corrosion resistance and mechanical hardness are very similar. The magnetic permeability can be as low as 1.005.
Summary of Composition and Vacuum Properties of Stainless Steels used for UHV.
Allectra GmbH was founded in 2002 in Berlin and now manufactures and supplies a full range of HV (high vacuum) and UHV (ultra high vacuum) components including custom products all over the world. Allectra Limited was started in 2003 in Sussex to promote the products on a worldwide basis. The Allectra sales and service network is also supported by offices in France and Italy. Today, global customers include universities, major Synchrotron laboratories and High Technology companies.