To improve the performance of stainless steel, we subjected solidstate steel to a nitrogen absorption treatment. In the fabrication process, a commercially available highchromium ferritic stainless steel (Fe22Cr1Mo) was heattreated at 1423 K in a nitrogen atmosphere. The heattreatment transformed the ferric phase into the austenite phase. This process loaded over 1 mass of nitrogen into the steel material. Most of the added nitrogen formed a solid solution in the matrix, but a minor portion formed nitrides with the very small quantities of elements such as titanium and aluminum that preexisted in the steel. The nitrogencontaining steels were then analyzed by pitting potential measurements and ferric chloride corrosion examination. The pitting corrosion resistance of Fe22Cr1Mo1N exceeded that of conventional materials such as Fe18Cr12Ni and Fe22Cr1Mo. However in the ferric chloride corrosion tests, pits developed in Fe22Cr1Mo1N at temperatures above 323 K. These pits were possibly initiated at the sites of minute nitride resulting from the nitrogen absorption process. [doi:10.2320/jinstmet.J2015004]
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