Abstract

Cavitation erosion behavior of nitrogen strengthened austenitic stainless steel in comparison to martensitic stainless steel

Author(s): Akhilesh K.Chauhan, D.B.Goel, S.Prakash

Nitrogen strengthened austenitic stainless steel (termed as 21-4-N steel) in as cast condition has been investigated as an alternative to 13/4 steel (termed as CA6NM) to overcome the problems of cavitation erosion in hydro turbine underwater parts. The cavitation erosion of 21-4-N and 13/4 steels was investigated by means of an ultrasonic vibration processor. As cast 13/4 steel finds wide application in hydroturbine underwater parts, this got eroded due to silt erosion and cavitation erosion. The cavitation erosion is highly depending on microstructure and mechanical properties. The results showthat 21-4-N steel ismore cavitation erosion resistant than the 13/4 steel. The eroded surfaces were analyzed through scanning electron microscopy and microhardness testing was also carried out at the cross section of the eroded surface for erosion mechanisms.