Effects of Nitrogen on Microstructure and Properties of 29Cr Cast Super Duplex Stainless Steel after Cryogenic Treatment

The effects of nitrogen content on microstructure, mechanical properties and corrosion resistance of 29Cr cast super duplex stainless steel after cryogenic treatment were studied by modern means of optical microscopy(OM), X-ray diffraction (XRD), environmental scanning electron microscopy (ESEM), universal testing machine, Rockwell hardness tester and electrochemical polarization curves. The results indicated that nitrogen could increase the amount of γ phase in the steel according to a linear relationship of (γ)=99.4×w(N)+6.158 8; and the higher the nitrogen content in the sample, the greater the tensile strength and the elongation; the increase of nitrogen could reduce the corrosion current density of the sample after cryogenic treatment, and improve the corrosion resistance.