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Microstructural effects on the rotating bending fatigue behavior of Ti-6Al-4V produced via laser powder bed fusion with novel heat treatments

Published

Author(s)

Nicholas Derimow, Jake Benzing, David Newton, Chad Beamer, Ping Lu, Frank DelRio, Newell Moser, Orion Kafka, Ryan Fishel, Lucas Koepke, Chris Hadley, Nik Hrabe

Abstract

The rotating bending fatigue (RBF) behavior (fully reversed, R = -1) of additively manufactured (AM) Ti-6Al-4V alloy produced via laser powder bed fusion (PBF-L) was investigated with respect to different microstructures achieved through novel heat treatments. The investigation herein seeks to elucidate the effect of microstructure by controlling variables that can affect fatigue behavior in Ti-6Al-4V, such as chemistry, porosity, and surface roughness. In order to control these variables, different hot isostatic pressing (HIP) treatments at 800 °C, 920 °C, and 1050 °C with a 920 °C temper were applied to three sets of Ti-6Al-4V cylinders that originated from the same PBF-L build, such that there were 30 tests per condition. After HIP treatment, the specimens were machined and tested. The highest runout stress was achieved after sub-β transus HIP at 800 °C for 2 hours at 200 MPa of pressure. A significant drop in fatigue strength was attributed to large prior-β grains and grain boundary α resulting from super-β transus HIP treated specimens. For the sub-β transus HIP specimens, differences in fatigue strength were attributed to α lath thickness, relative dislocation density, and dislocation boundary strengthening.
Citation
International Journal of Fatigue

Keywords

additive manufacturing, Ti-6Al-4V, Rotating bending fatigue, heat treatment, laser powder bed fusion

Citation

Derimow, N. , Benzing, J. , Newton, D. , Beamer, C. , Lu, P. , DelRio, F. , Moser, N. , Kafka, O. , Fishel, R. , Koepke, L. , Hadley, C. and Hrabe, N. (2024), Microstructural effects on the rotating bending fatigue behavior of Ti-6Al-4V produced via laser powder bed fusion with novel heat treatments, International Journal of Fatigue, [online], https://doi.org/10.1016/j.ijfatigue.2024.108362, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=957594 (Accessed May 27, 2024)

Issues

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Created April 30, 2024