Response of different electron beam melting produced Alloy 718 microstructures to thermal post-treatments
Journal article, 2020

Electron beam melting (EBM) was used to produce Alloy 718 specimens with different microstructures (columnar, equiaxed and a combination thereof) by varying the process parameters. The present study aimed at assessing the response of such varying as-built microstructures to identical thermal post-treatments, which included hot isostatic pressing (HIPing) followed by heat treatment involving solution treatment and aging. The effect of these treatments on defect content, grain structure, hardness and phase constitution in the specimens was specifically analysed. Despite differences in defect content of as-built specimens with distinct microstructures, HIPing was effective in closing defects leading to samples exhibiting similar density. After HIPing, grains with equiaxed morphology or columnar grains with lower aspect ratio showed higher tendency for grain growth in comparison to the columnar grains with higher aspect ratio. The various factors affecting the stability of grains during HIPing of builds with distinct microstructures were investigated. These factors include texture, grain size, and secondary phase particles. The carbide sizes in the different as-built samples varied but were found to be largely unaffected by the post-treatments. Solution treatment following HIPing led to greater precipitation of grain boundary δ phase in regions with coarser grains than the smaller ones. After HIPing and heat treatment, all specimens exhibited similar precipitation of γ″ phase regardless of their grain morphology in the as-built condition.

Post treatment

Electron beam melting



Additive Maunufacturing


Tejas Gundgire

University West

Sneha Goel

University West

Uta Klement

Chalmers, Industrial and Materials Science, Materials and manufacture

Shrikant Joshi

University West

Materials Characterization

1044-5803 (ISSN)

Vol. 167 110498

Subject Categories

Materials Engineering

Metallurgy and Metallic Materials

Areas of Advance




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