Dynamic strain ageing of an austenitic superalloy—Temperature and strain rate effects

The tensile data involving austenitic Alloy C-276 suggest that this alloy is capable of maintaining appreciable structural strength at temperatures relevant to the sulfuric acid decomposition process related to the nuclear hydrogen initiative. Reduced failure strain and formation of serrations, characteristics of dynamic strain ageing (DSA), were noted within susceptible temperature regimes. An average activation energy of 55 kJ/mol, and work hardening index ranging from 0.68 to 0.75 were determined as functions of different testing temperature and strain rates. The occurrence of DSA was also associated with enhanced dislocation density. Depending on the testing temperature, a combination of ductile and intergranular brittle failures was observed with the tested specimens.