A novel cast & wrought FGH4096 superalloy with refined microstructures prepared by electron beam drip melting technology and its homogenization behavior

Abstract

The first proposal of using Electron beam drip melting (EBDM) technology to prepare 〈001〉 oriented columnar grain superalloy was prepared. The study investigated the effects of the EBDM on the microstructure of FGH4096 alloy and the evolution of microstructure during the homogenization process, providing a solid foundation for subsequent thermal deformation processes. Compared to traditional melting methods, the secondary dendrite arm spacing of the EBDM alloy has been significantly reduced by over 40 %, with a 47.5 % decrease in the size of the γ’ phase in the dendrite arm regions. The size of the γ’ phase in the interdendritic regions has decreased by 28.9 %. The size and number of pores in superalloys produced by EBDM are significantly reduced, with a decrease in porosity of approximately one order of magnitude. The high temperature gradients and melt convection effects in the EBDM process promote an increase in the solute boundary layer thickness, significantly reducing both macroscopic and microscopic segregation. The EBDM process can generate relatively high internal residual stresses. By conducting homogenization treatment to control crystal orientation, it is possible to retain the advantages of columnar grain thermal deformation while using the residual stresses that are retained to provide activation energy for subsequent thermal deformation processes. This significantly enhances the thermal deformation capabilities of FGH4096 alloy.