Preparation of High Nitrogen Containing Stainless Steels by Mechanical Alloying Method and Their Localized Corrosion Behavior
Tomokazu FUKUTSUKA, Tetsuya ANZAI, Mami KANEDA, Yoshiaki MATSUO, Yosohiro SUGIE and Kenzo FUKAURA
Abstract:High nitrogen containing stainless steel was prepared by mechanical alloying (MA) method from SUS 447 powder. The SUS 447 powder was ball-milled at N2 atmosphere and then HIP treatment was carried out. The obtained stainless steels were examined by X-ray diffraction (XRD) and scanning electron microscope (SEM). With the increase in the time of MA treatment, dissolved nitrogen content of the stainless steel was increased, and ferrite phase changed into austenite phase. The evaluation of corrosion behavior was carried out by the electrochemical corrosion test. For the stainless steel with MA treatment without nitrogen, it was found that the pitting potential in sulfuric acid solution including the chloride was very noble. And clear pitting corrosion was not observed for the stainless steel with MA treatment with nitrogen. The results of electrochemical corrosion test indicated that localized corrosion was suppressed by the MA treatment. Key Words:Mechanical alloying, Stainless steel, Nitrogen, Localized corrosion, Pitting corrosion