In this study,Alloy 718 specimens were fabricated via selective laser melting(SLM),and the effects of different post-treatments on microstructures and mechanical properties of the alloy were systematically studied.The...In this study,Alloy 718 specimens were fabricated via selective laser melting(SLM),and the effects of different post-treatments on microstructures and mechanical properties of the alloy were systematically studied.The post-treatment techniques investigated were solid solution+dual aging(SA) and hot isostatic pressing+solid solution+dual aging treatment(HIP+SA).The results indicate that the specimens treated using SA have a columnar crystal structure similar to the as-built sample,the microstructure is partially recrystallized,and the grain size increases slightly.Meanwhile,the grain morphology is dominated by equiaxed crystals in samples treated using HIP+SA,and the microstructure is completely recrystallized,with distinct grain coarsening and a large number of twins formed.Specimens treated using SA and HIP+SA show high tensile strength and yield strength and excellent elongation at room temperature,which can be primarily attributed to the strengthening of the γ’ and γ "precipitated phases.The number of γ" precipitated phases are reduced due to the consumption of Nb to form a large amounts of δ phase and(Ti,Nb)C carbides,resulting in the strength of HIP+SA specimens being lower than that of SA specimens.展开更多
基金financially supported by the Key-Area Research and Development Program of Guangdong Province (No.2018B090905001)Guangdong Science and Technology Project (No.2018B090905002)+1 种基金Guangzhou Science and Technology Project (No.201807010075)Dongguan Introduction Plan of Research Team (No.201536000200027)。
文摘In this study,Alloy 718 specimens were fabricated via selective laser melting(SLM),and the effects of different post-treatments on microstructures and mechanical properties of the alloy were systematically studied.The post-treatment techniques investigated were solid solution+dual aging(SA) and hot isostatic pressing+solid solution+dual aging treatment(HIP+SA).The results indicate that the specimens treated using SA have a columnar crystal structure similar to the as-built sample,the microstructure is partially recrystallized,and the grain size increases slightly.Meanwhile,the grain morphology is dominated by equiaxed crystals in samples treated using HIP+SA,and the microstructure is completely recrystallized,with distinct grain coarsening and a large number of twins formed.Specimens treated using SA and HIP+SA show high tensile strength and yield strength and excellent elongation at room temperature,which can be primarily attributed to the strengthening of the γ’ and γ "precipitated phases.The number of γ" precipitated phases are reduced due to the consumption of Nb to form a large amounts of δ phase and(Ti,Nb)C carbides,resulting in the strength of HIP+SA specimens being lower than that of SA specimens.
