Corrosion resistance of carbonitriding stainless steels in chloride solutions

This paper presents results from study of corrosion behaviour of plasma carbonitriding of stainless steels (00H18 N9, 00H18N9Mo, 00H21N19Si and L00H21N7MCU.) surfaces. The carbonitriding process was performed with application of plasma assisted chemical vapour deposition techniques, in MWCVD (2,45 GHz, 350 W) system. In the prosess a mixture of CH4, N-2, and H-2 gases was introduced to the reactor. MW plasma carbonitriding was conducted under low pressure and low temperature conditions (0,8 Tr, 400 degrees C). The treatment surface was investigated using, XPS methods. The corrosion behaviour of the steels was studied on the base of polarisation (LSV) curves in 3% NaCl solution. The carbonitriding surfaces have a better ability to passivation. Moreover, the treatment surface of the 00H21N19Si5M steel shows a higher corrosion rsistance to pitting corrosion.