Anisotropy of flow behavior and microstructure evolution of selective laser melted 718 alloy during high temperature deformation

Abstract

The uniaxial hot compression tests of selective laser melted (SLM) 718 alloy with different orientations were carried out by thermal simulation tester, and the microstructure of the as-built and deformed samples was analyzed by scanning electron microscope (SEM) and electron backscattered diffraction (EBSD) technologies. The results indicate that the orientation of the sample has little effect on the variation of flow stress, but it has a certain impact on the value of the peak stress. The constitutive equation could accurately predict the flow behavior of two orientations samples, and the calculated activation energies (Q) values of the H-orientation samples is 517.07 kJ/mol, which is slightly lower than 543.77 kJ/mol of V-orientation samples. The analysis of microstructure shows that the dynamic recrystallization (DRX) process in the H-orientation samples is more likely to occur than that in V-orientation samples under the same deformation conditions, which is caused by the difference in the evolution of initial deformed grains of the two orientations samples during deformation.