100.000h PERFORMANCE OF SUPERALLOYS IN GT

The purpose of this paper is to review corrosion processes and experience related to the good performance of gas turbines forover 100 000h operation. Some of the main features of the high temperature corrosion of superalloys concerning the interaction between contaminants and the establishment of protective scale have been explained . the important competition between surface Cr2o3 scale development and internal corrosion penetration is emphasized and extended to explain the existence or not of an incubation period, the temperature dependence and contamiamt flux, under , the real operating conditions of the GT S. the empgasis here is made to further understand the mechanism of protection which was afforded by several supperalloys, through detailed microstructural and morphological investigation of Cr2o3 scale. Such understanding is necessary if advances in hot section turbine material are to be achieved.