Tag Archives: ASTM A193 B8LNA

Non Magnetic B8LN Stainless Steel Fasteners

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The ultimate non-magnetic stainless steel fasteners are manufactured in extremely small quantities by Hague Fasteners.

The high Nitrogen content of ASTM A193 B8LN fasteners (304LN fasteners) creates an extremely low level of magnetic permeability and these special fasteners are used when is used where an extremely low level of magnetic permeability is required.

Special Fasteners in this specific stainless steel further exhibit the following desirable properties:-

Moderate pitting and crevice corrosion resistance
Excellent impact toughness at sub-zero temperatures
A higher proof stress yield than regular 304L stainless steel fasteners.
Non-magnetic, Very low ferrite level and very resistant to martensitic transformation. Relative magnetic permeability < 1.005 Good weldability. 304LN was originally developed as a higher strength version of 304L by raising the amount of nitrogen. However, the increase in strength is only modest and easily achieved through cold working. Further, duplex grades are now commonly used where higher strength bolting is required. The grade is now used in specialised applications where a very low magnetic response is needed. In standard 304L, a typical level of relative magnetic permeability is around 1.05-1.1 due to small amounts of ferrite in the austenitic structure. A completely non-magnetic material would have a value of 1.0. 304LN can achieve a maximum value of around 1.005, which is the lowest practical level of any steel grade. It is also very resistant to transformation to the magnetic martensitic phase which can occur on forming or cooling to very low temperatures. For this reason Hague's manufactured B8LN Special Fasteners are commonly used in specialised equipment where magnetic “interference” needs to be avoided and also for use in cryogenic equipment such as bolting for Magnetic resonance imaging (MRI) scanners, reinforcing foundation bolts for structures surrounding MRI scanners also special fasteners in pressure vessels, and non standard socket screws in cryogenic applications.