Comments on ‘microstructural evolution of hydroformed inconel 625 bellows’

Abstract : In a recent paper, E. Pavithra and V.S. Senthil Kumar [Journal of Alloys and Compounds 669 (2016) 199] studied the microstructure evolutions during fatigue of hydroformed bellows made of Alloy 625. The authors made several shortcuts in their analysis of microstructure evolutions after two fatigue tests performed at room temperature and at 650 °C. Moreover, the conclusions of the paper are not supported by the very poor SEM observations provided in this paper. The aim of the present comments is to reconsider these results based on the available literature on the microstructure evolutions and fatigue properties of Alloy 625.