Formation of nitrided layers on duplex steeinfluence of multiphase substrate

摘要

The present paper reports the results of gas nitriding of duplex stainless steel and study of the effect of substrate structure on the nitrided layers. The differences in the growth of the layers on austenitic and ferritic substrate were studied. The microstructure and phase composition of the layers were investigated using light microscopy analysis), X-ray diffraction (XRD and grazing angle XRD - GXRD) and electron microprobe spectrometry. Moreover, the microhardness of the layers was studied. A particular role of steel substrate in layer formation was observed at a low temperature (below 500°C) nitriding. The layers were mostly composed of the S phase and expanded martensite formed on austenite and ferrite grains respectively. The substrate influence was of minor importance at treatment temperature higher than 500°C.