Investigation of gamma precipitation process under effect of strain in Nimonic80A nickel base superalloy

Gamma-prime precipitation behavior under the influence of strain in Nimonic80A superalloy was investigated using stress relaxation test in the temperature range of 900-900°C and strain rate of 0.001 s-1. The dissolution and deposition temperature of gamma-prime phase in the present study is in the temperature range of 950°C to 960°C, which was determined using thermal analysis. The results show that the dissolution temperature of gamma prime or precipitation is a function of the temperature and the amount of strain applied. Actually, with increasing the temperature of stress relaxation test, the precipitation onset times in the temperature range of 900°C to 950°C decreased and then increased at 975°C. Also, at 1000°C at a strain of 0.05, no precipitation was observed in the sample, but with increasing strain of 0.2, precipitation occurred first and over time has been resolved again in the field. The dissolution temperature of gamma pram s precipitation at low strains (0.05) is not affected by strain (unlike strain 0.2). precipitation-time-temperature (PTT) curve for Nimonic80A superalloy was plotted and investigated using the start and end times of precipitation obtained from stress release curves. Also, the microstructure of the samples was examined and analyzed in order to verify the results of stress relaxation test using scanning electron microscope (FESEM).