PARK Kyung-Tae

Spoluautoři HWANG Si Woo

The hot deformation behavior of NIMONIC 80A was studied in the temperature range of 900 ~ 1200°C by employing the hot compression tests with the strain rates varying between 0.02~20 s-1. The results showed that the strength during hot compression increased with increasing the strain rate and decreasing temperature. Hot deformation of NIMONIC 80A was well-described by the sinh creep law with the stress exponent of 4.5 and the activation energy of 425 kJ/mol. Processing maps were also constructed on the basis of a dynamic material model. At low strains, the processing map of NIMONIC 80A did not reveal any instability domain regardless of the strain rate and temperature. However, at high strains, the processing map exhibited an instability domain at a low strain rate of 0.2 s-1 and within a temperature range of 900 ~ 1000°C. In the instability domain, recrystallization did not occur and the deformed microstructure exhibited shear bands and carbide precipitation while full recrystallization occurred in the safe domain.