SAF2906　is　a　new　kind　of　super　duplex　stainless　steel,　and　more　corrosion-resistant　and　strong　than　SAF2507,　suitable　to　be　used　in　the　low　temperature　and　corrosion　conditions.　In　order　to　prevent　the　occurrence　of　microstructure　changes　resulting　in　the　property　deterioration,　in　the　general,　the　castings　made　for　SAF2906　should　be　cryogenically　treated　before　they　are　used　in　the　ultra　low　conditions.　N　is　an　alloying　element,　usually　added　to　stainless　steels　to　increase　the　material　properties.　So,　In　this　paper,　the　effects　of　N　content　on　microstructure,　mechanical　and　corrosion　resistance　properties　of　SAF2906　casting　super　duplex　stainless　steel　(SDSS)　after　cryogenic　treatment　were　studied　by　means　of　Optical　Microscope(OM),　X-ray　Diffraction(XRD)　and　electrochemical　workstation.　The　results　indicate　that　N　can　increase　the　amount　of　γ　phase　according　to　a　linear　relationship　of　Φ(γ)=99.4×w(N)+6.16.　When　N　content　is　low　or　medial,　γ　phase　can　precipitate　from　ferrite.　When　N　content　is　high,　γ　phase　does　not　precipitate　from　ferrite　and　is　converted　directly　from　ferrite　and　austenite　grain　boundaries.　The　higher　N　content,　the　greater　tensile　strength　and　elongation,　the　better　corrosion　resistance.　Compared　with　solution　state,　cryogenic　treatment　can　improve　corrosion　resistance.　©　(2010)　Trans　Tech　Publications.