Effect of post-treatments under hot isostatic pressure on microstructural characteristics of EBM-built Alloy 718

Goel, Sneha,1993-Högskolan Väst,Avdelningen för avverkande och additativa tillverkningsprocesser (AAT) (author)

Electron beam melting (EBM) has emerged as an important additive manufacturing technique. In this study, Alloy 718 produced by EBM was investigated in as-built and post-treated conditions for microstructural characteristics and hardness. The post-treatments investigated were hot isostatic pressing (HIP) and combined HIP + heat treatment (HIP + HT) carried out as a single cycle inside the HIP vessel. Both the post-treatments resulted in significant decrease in defects inevitably present in the as-built material. The columnar grain structure of the as-built material was found to be maintained after post-treatment, with some sporadic localized grain coarsening noted. Although HIP led to complete dissolution of δ and γ′′ phase, stable NbC and TiN (occasionally present) particles were observed in the post-treated specimens. Significant precipitation of γ′′ phase was observed after HIP + HT, which was attributed to the two-step aging heat treatment carried out during HIP + HT. The presence of γ′′ phase or otherwise was correlated to the hardness of the material. While the HIP treatment resulted in drop in hardness, HIP + HT led to ‘recovery’ of the hardness to values exceeding those exhibited by the as-built material.

Sittiho, AnumatUniversity of Idaho,University of Idaho, Department of Chemical and Materials Engineering, Moscow, ID 83844, United States (author)
Charit, IndrajitUniversity of Idaho,University of Idaho, Department of Chemical and Materials Engineering, Moscow, ID 83844, United States (author)
Klement, Uta,1962Chalmers tekniska högskola,Chalmers University of Technology,Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg, Sweden(Swepub:cth)uk (author)
Joshi, Shrikant V.,1960-Högskolan Väst,Forskningsmiljön produktionsteknik(PTW),PTW(Swepub:hv)shrjos (author)
Högskolan VästAvdelningen för avverkande och additativa tillverkningsprocesser (AAT) (creator_code:org_t)

By the author/editor: Goel, Sneha, 199 ...; Sittiho, Anumat; Charit, Indrajit; Klement, Uta, 19 ...; Joshi, Shrikant ...

About the subject

ENGINEERING AND TECHNOLOGY: ENGINEERING AND ...; and Materials Engine ...; and Other Materials ...

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