Microstructural evolution of subsurface on Inconel 690TT alloy subjected to fretting wear at elevated temperature

• Published in: Materials & design 2016-08, Vol.104, p.152-161
• Main Authors: Xin, L., Yang, B.B., Wang, Z.H., Li, J., Lu, Y.H., Shoji, T.
• Format: Article
• Language: English
• Subjects: Evolution; Fretting; Fretting wear; Microstructure; Nickel base alloys; Nickel based superalloys; Oxidation; Oxides; Plastic deformation; Superalloys; Wear
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2016.05.030

The subsurface layers underneath the worn surface of Inconel 690 alloy subjected to dry fretting wear at 220°C in air were characterized. The results indicated that there are five layers: oxide layer, mixed layer, TTS layer, plastic deformation layer and base materials in the subsurface. In addition, duplex microstructure evolution took place during the fretting wear. The stable oxide layer of NiCr2O4 and Fe2O3 formed on the worn surface due to the sufficient oxidation and persistent mechanical effect, while the oxygen easily penetrated into TTS layer, which produced the mixed zone consisting of ultra-fine metal grains and oxides of NiO and Cr2O3. Amorphous structure was found in the interface between TTS and mixed zone due to the crystal defects and atomic disorder. The equiaxed-grained TTS layer formed as a consequence of large plastic strain by dynamic recrystallization, leading to disappearance of carbides in the grain boundary. Moreover, in the plastic deformation layer, grain refinement was controlled by formation of dislocation tangles and walls. Typical microstructure evolution in subsurface of Inconel 690TT alloy during fretting wear. [Display omitted] •Oxide layer, mixed layer, TTS, plastic deformation layer formed in the subsurface.•Oxide layer included NiCr2O4 and Fe2O3 due to full oxidation and mechanical effect.•Mixed zone consisted of metal nanograins and oxides including NiO and Cr2O3.•Recrystallization resulted in formation of TTS and disappearance of carbides.•Amorphous structure was found in the interface between TTS and mixed zone.