304LN is used where an extremely low level of magnetic permeability is required. This derives from its high nitrogen content. Approximate Composition – 18% Cr, 9% Ni, 0.15% N (Exact composition ranges vary between EN and ASTM standards). This grade combines the following characteristics: 1、Moderate pitting and crevice corrosion resistance 2、Excellent impact toughness at sub-zero temperatures 3、Higher 0.2% PS than 304L 4、Non-magnetic. Very low ferrite level and very resistant to martensitic transformation. Relative magnetic permeability < 1.005 5、Good weldability. Care needed to avoid solidification cracking 304LN stainless steel was originally developed as a higher strength version of 304L using nitrogen. However, the increase in strength is only modest and duplex grades are now mostly used for this purpose. 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. Therefore, its main uses are in specialised equipment where magnetic “interference” needs to be avoided and/or for use in cryogenic equipment. STANDARDS INDUSTEEL TRADEMARKS UNS ASTM EURONORMS EN SUS UR™ 304LN S30453 304LN 1.4311 X2CrNiN18-10 SUS 304LN CHEMICAL ANALYSIS (%WEIGHT) C Cr Ni Mo N Others < 0,030 18,5 8,5 - 0,15 PROPERTIES 0,2 Y.S. - Rp 0,2min ASTM / EN 0,2 Y.S. - Rp 0,2(2)typical value UTS - Rm min ASTM / EN UTS - Rm(2)typical value EI-A(1)% PREN(4) HOMOLOGATIONS MPa Ksi MPa Ksi MPa Ksi MPa Ksi Last revised 270 39 335 49 550 80 630 91 45 21