Abstract
Electron beam melting (EBM) is gaining rapid popularity for production of complex customized parts. For strategic applications involving materials like superalloys (e.g., Alloy 718), post-treatments including hot isostatic pressing (HIPing) to eliminate defects, and solutionizing and aging to achieve the desired phase constitution are often practiced. The present study specifically explores the ability of the combination of the above post-treatments to render the as-built defect content in EBM Alloy 718 irrelevant. Results show that HIPing can reduce defect content from as high as 17% in as-built samples (intentionally generated employing increased processing speeds in this illustrative proof-of-concept study) to <0.3%, with the small amount of remnant defects being mainly associated with oxide inclusions. The subsequent solution and aging treatments are also found to yield virtually identical phase distribution and hardness values in samples with vastly varying as-built defect contents. This can have considerable implications in contributing to minimizing elaborate process optimization efforts as well as slightly enhancing production speeds to promote industrialization of EBM for applications that demand the above post-treatments.
Highlights
Electron beam melting (EBM) is a powder bed fusion-based metal additive manufacturing (AM)technique bearing capability to produce components with high design flexibility
Anisotropy in tensile behavior of heat-treated EBM Alloy 718 has been attributed to remnant defects [9,10]
The present study explores the potential of the combined post-treatments involving hot isostatic pressing (HIPing), solutionizing and aging treatment to test the hypothesis of whether they can render the as-built defect content in EBM Alloy 718 irrelevant
Summary
Electron beam melting (EBM) is a powder bed fusion-based metal additive manufacturing (AM). Use of unoptimized process parameters has been shown to result in extensive defect formation [8] Such defect formation in EBM Alloy 718 can have adverse consequences, as defects can degrade mechanical behavior of the EBM-built material. The HIP’ed material is typically subjected to solution treatment and aging to achieve the required phase composition In this context, it is pertinent to mention that the typical recommended parameters for HIPing are 1120–1185 ◦ C, 100 MPa,. The present study explores the potential of the combined post-treatments involving HIPing, solutionizing and aging treatment to test the hypothesis of whether they can render the as-built defect content in EBM Alloy 718 irrelevant. The extent of defects incorporated far exceeded those typically encountered in EBM builds for the sake of this illustrative proof-of-concept study
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