The normally used British Standards for these in the past have been

BS970 - Wrought steels for mechanical and allied engineering purposes Part 1:1991 General inspection and testing procedures and specific requirements for carbon, carbon manganese, alloy and stainless steels

BS1449 - Steel plate, sheet and strip Part 2:1983 Specification for stainless and heat resisting steel plate, sheet and strip

A range of new British Standards have been issued which supersede both of the above.  The terminology is ‘messy’ but the important ones relating to properties are

BS EN 10088-2:1995 – Technical delivery conditions for sheet/plate and strip for general purposes (replaces BS1449 Part 2)
BS EN 10088-3:1995 - Technical delivery conditions for semi finished products, bars, rods, and sections for general purposes (replaces most of BS970)

Being a ‘Eurocode’ the BS EN range does not use either the UK or USA naming methods.  Instead, the numbering system similar to that used by Germany is used.

 Thus grade 304 became 1.4301

1. = steel    43 = group of stainless steels    01 = grade identification

Fasteners

The system used for fasteners is totally different to that used for plates etc.

Basically the specification consists of two parts, which give the degree of stainlessness and the strength.

The steel grades are

A1 - Chromium-nickel steel (sometimes called free-machining grade 303/1.4305).  Corrosion resistance is reduced and it is not suitable for coastal or industrial environments. This grade should not normally be specified

A2 - Chromium-nickel steel (grade 304/1.4301) suitable for rural, urban and light industrial.

A4 - Chromium-nickel-molybdenum steel (grade 316/1.4401) suitable for industrial and coastal areas.

The grades given are not true equivalents as they are strengths whilst the letters are for stainlessness.  They are however often quoted (wrongly) in specifications. The letter A in the above stands for austenitic.  This is the common type of stainless steel and can be readily formed and welded.

Other types which may be mentioned are martensitic (stronger but cannot usually be welded), and ferritic (less strong).

The property classes are

50 -  Softened

70 -  Cold worked

80 - High strength

In theory any grade can be mixed with any class.  However in practice the most common combinations are A2 70, A2 80, A4 80.  Many suppliers say that class 50 is not easy to obtain and can in fact carry a cost penalty if insisted upon.