Deformation behavior and microstructure evolution of nickel-based superalloys fabricated by selective laser melting

In this study, the thermal deformation behavior of GH3230 alloy fabricated by selective laser melting (SLM) was investigated for the first time by isothermal hot compression tests in the temperature range of 850∼1150 °C and the strain rate range of 0.01∼1 s -1 . The influence of different thermal deformation parameters on the high-temperature rheological behavior of GH3230 alloy was investigated, and the constitutive equation and thermal processing map were established according to the rheological stress. The microstructure evolution and dynamic recrystallization (DRX) behavior of GH3230 after thermal deformation were investigated. The results showed that the flow stress decreased with the increase of temperature and the decrease of strain rate. The relationship between the flow stress, strain rate and deformation temperature of GH3230 alloy was suitable for the hyperbolic sine equation. When the strain was 0.7, the activation energy value of the GH3230 alloy's thermal deformation was 505.44246 KJ mol -1 , and the prediction correlation coefficient of the strain-compensated Arrhenius constitutive model was all above 0.99. Dynamic precipitation and DRX occurred in the hot deformation zone, and dynamic precipitation preceded DRX. With the temperature increasing from 850 °C to 1150 °C, the DRX mechanism changed from discontinuous dynamic recyclizations (DDRX) to continuous dynamic recrystallization (CDRX). It was mainly due to the change of dislocation motion behavior with the increase of deformation temperature. This study presents for the first time the thermal deformation behavior of GH3230 formed SLM and discovers the mechanism transition from DDRX→CDRX. This study will provide guidance for the actual industrial application of SLM-formed GH3230 alloy.