Exploring grinding and burnishing as surface post-treatment options for electron beam additive manufactured Alloy 718

• Published in: Surface & coatings technology Vol. 397; p. 126063
• Main Authors: Karthick Raaj, R., Vijay Anirudh, P., Karunakaran, C., Kannan, C., Jahagirdar, Adwait, Joshi, Shrikant, Balan, A.S.S.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15-09-2020; Elsevier BV
• Subjects: Additive manufacturing; Aerospace industry; Burnishing; Compressive properties; Compressive residual stress; EBAM; Electron beams; Grinding; Lead time; Low plasticity burnishing; Microhardness; Nickel; Nickel base alloys; Porosity; Post-treatment; Process variables; Production Technology; Produktionsteknik; Residual stress; Superalloys; Surface finish; Surface roughness; Surface treatment; Titanium base alloys; EBAM; Surface roughness; Post-treatment; Grinding; Compressive residual stress; Low plasticity burnishing; Automobile manufacture; Additives; Nickel alloys; Grinding (machining); Marine applications; Burnishing; Residual stresses; Superalloys; Surface post-treatment; Microhardness; Titanium alloys; 3D printers; Electron beams; Sequential combination; Automotive industry; Residual stress profiles; Surface residual stress; Nickel- based superalloys; High performance applications
• ISSN: 0257-8972; 1879-3347; 1879-3347
• DOI: 10.1016/j.surfcoat.2020.126063

Numerous additive manufacturing (AM) techniques have been developed over the past decade. Features like immense freedom of intricate part design and shorter lead time make AM routes promising for a wide range of applications spanning aerospace, marine and automobile sectors. Among the various metal AM processes, Electron Beam Additive Manufacturing (EBAM) is being widely explored to realise the potential of Ni-based superalloys and Ti alloys for varied high-performance applications. A novel attempt has been made in this paper to assess the surface integrity of as-built EBAM nickel-based superalloy 718 (AB) subjected to grinding (G), Low Plasticity Burnishing (LPB) and their sequential combination. Apart from their influence on sub-surface microstructures, the effect of process variables during the above post-treatments on the residual stress profiles was also investigated. Results revealed that G + LPB results in about 0.6 μm lower surface roughness, 17% improved microhardness compared to AB + LPB, and higher compressive surface residual stress as compared to LPB processed EBAM samples. The sequential grinding and LPB - improved microhardness, was also found to extend about 500 μm more when compared to the LPB process. The G + LPB, which is greatly influenced by the prior grinding, smoothens the surface and thus results in a better surface finish. Highest hardness, superior surface finish, reduced porosity and improved compressive residual stress were observed in samples that adopted the AB + G + LPB sequence over other samples, with the LPB step at 40 MPa yielding the best results.
•Evaluation of low plasticity burnishing pressure influence on EBAM components•Combined grinding and burnishing influence on EBAM part is enquired.•Exhaustive microstructural and microporosity analysis on post-treated EBAM parts•Determination of optimal post-treatment and surface integrity for EBAM parts•Higher degree microporosity reduction and meliorated hardness observed at 40 MPa