In-process failure analysis of thin-wall structures made by laser powder bed fusion additive manufacturing. (30th January 2022)

• Record Type: Journal Article
• Authors: Chakraborty, Apratim; Tangestani, Reza; Batmaz, Rasim; Muhammad, Waqas; Plamondon, Philippe; Wessman, Andrew; Yuan, Lang; Martin, Étienne
• Is Part Of: Journal of materials science & technology. Volume 98(2022)
• Page Start: 233
• Page End: 243
• Publication Date: 2022-01-30
• Subjects: Laser powder bed fusion -- Superalloys -- Thin-wall -- Residual stress -- Additive manufacturing; Metals -- Periodicals; Materials science -- Periodicals; Materials science; Metals; Periodicals; 620.1105
• DOI: 10.1016/j.jmst.2021.05.017
• Languages: English
• ISSNs: 1005-0302

Abstract

Highlights: Build failure in laser additive manufacturing heavily affected by part thickness. Reduction of limiting build height in thin-wall structures not caused by cracking. In-process stresses promote thin-wall part failure due to significant distortion. Abstract: Fabrication of thin-wall components using the laser powder bed fusion (LPBF) additive manufacturing (AM) technology was investigated for two "hard-to-weld" high gamma prime Ni-based superalloys RENÉ 65 (R65) and RENÉ 108 (R108). Simple block parts with wall thicknesses of 0.25 mm, 1.00 mm, and 5.00 mm are printed using a bidirectional laser scanning strategy without layer-wise rotation. Parts with walls thinner than 5 mm fail before reaching the designated build height. Results indicate that reduction of limiting build height (LBH) corresponds to the reduction of part thickness and is unaffected by alloy composition. On the contrary, the number of internal micro-cracks along columnar grain boundaries in the build direction (BD) increases with part thickness and is significantly higher in R108 than R65. These findings suggest that reduced LBH in parts with thinner walls is not caused by internal micro-crack formation. Fractography and finite element analysis (FEA) of the in-process thermal stresses show that the LBH trend is not explained by the conventional cracking mechanism. Simulations suggest that part thickness affects stress distribution leading to more substantial distortion and consequent failure to add layers for continued fabrication of thinner parts. Graphical abstract: Image, graphical abstract