High Nitrogen Corrosion Resistant Austenitic Stainless Steels Produced by HIP P/M Processing

The development, production experience and properties of high nitrogen austenitic stainless steels produced from nitrogen gas atomized powders consolidated by hot isostatic pressing or extrusion are described. These steels, which contain 3.5-8.5 Mn, 24-28 Cr, 22 Ni, 6-8 Mo and 0.45-0.90 N, exhibit an excellent combination of strength, ductility and corrosion resistance in the solution treated condition. Alloy development efforts indicate that variation of the major alloying elements not only influences the nitrogen solubility but also effects the corrosion resistance, ductility and toughness properties. In the solution treated condition, the steels exhibit tensile yield strengths as high as 700 MPa with over 60% ductility and FeCl 3 critical pitting and crevice corrosion temperatures in excess of 95°C. Successful atomization in heat quantities of up to 2,300 kg indicates that induction melting and gas atomization is a viable production method for these high nitrogen materials.