Effects of strain rate and temperature on mechanical property of nickel-based superalloy GH3230

High temperature tensile tests of nickel-based superalloy GH3230 were carried out at various strain rates from 10^-3 s^-1 to 10^-1 s^-1 over temperature range from 1144 K to 1273 K. The emphasis has been put on the effect of strain rate and temperature on the plastic flow stress. The results show that flow stress increases and the hardening exponent n decreases with the strain rate increasing or temperature decreasing. The strain rate sensitivity exponent m is a constant independent of temperature according to the interdependencies of flow stress, strain rate and temperature. The thermal deformation activation energy of GH3230 was calculated as 441 kJ/mol. The full recrystallization will occur when the temperature is about 1273 K and the microstructures with uniform and fine grains can be obtained. The SEM result shows that the fracture mode of all specimens is micro-porous aggregation ductile fracture caused by damage, the variation of temperature has not much effect on fracture morphology at various temperatures, but fracture dimple becomes deeper and larger while the strain rate decreasing.