Subsurface grain refinement in electron beam-powder bed fusion of Alloy 718: Surface texture and oxidation performanceShow others and affiliations
2020 (English)In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 168Article in journal (Refereed) Published
Abstract [en]
Subsurface grains of Alloy 718 additively manufactured via electron beam-powder bed fusion technique were refined using shot peening to improve the surface texture and oxidation performance. Oxidation of the specimens was performed at 650 and 800 degrees C in ambient air. Due to plastic deformation upon shot peening, compressive residual stress and high microstrain were generated in the subsurface region within a depth of approximately 50 mu m. The shot-peened specimen exhibited lower surface roughness, finer subsurface grains, and higher hardness compared to the as-built specimen. Shot peening, coupled with hot isostatic pressing and heat treatment (HIP-HT), yielded superior oxidation performance with substantially low oxidation kinetics at 800 degrees C. The smooth surface, as well as dense and refined subsurface microstructure resulting from shot peening, facilitated the formation of a continuous, protective, and adherent Cr-rich oxide scale.
Place, publisher, year, edition, pages
Elsevier, 2020. Vol. 168
Keywords [en]
Powder bed fusion; Alloy 718; Shot peening; Grain refinement; Surface texture; Surface characterization
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
URN: urn:nbn:se:hv:diva-17201DOI: 10.1016/j.matchar.2020.110567ISI: 000571490200001Scopus ID: 2-s2.0-85089745298OAI: oai:DiVA.org:hv-17201DiVA, id: diva2:1622055
Funder
Knowledge Foundation, 20180203
Note
Financial supports of the Knowledge Foundation for the SupREme project (Dnr 20180203) and Aforsk for the SCC-SUMAN project (18-296) are highly acknowledged. The authors would like to thank Mr. Jonas Olsson, Dr. Mahdi Eynian, and Prof. Joel Andersson for their valuable help and advice in processing and characterization of the specimens. The authors would like to thank Mr. Olle Widman from Curtiss-wright Surface Technologies for shot peening, Mr. Johannes Gardstam, and Mr. James Shipley from Quintus Technologies AB for HT-HIPing of the specimens. The authors are grateful to Venkataramanan Mohandass for the characterization of the specimens. Chalmers Materials Analysis Laboratory (CMAL) at the Chalmers University of Technology are appreciated for the help in the XRD/SEM analysis.
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