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Title: Effects of Scanning Strategy on Residual Stress Formation in Additively Manufactured SS 17-4 PH
Parts fabricated via directed energy additive manufacturing (AM) can experience very high, localized temperature gradients during manufacture. These temperature gradients are conducive to the formation of a complex residual stress field within such parts. In the study, a thermo-mechanical model is employed for predicting the temperature distribution and residual stress in Ti-6Al-4V parts fabricated using laserpowder bed fusion (L-PBF). The result is utilized for determining a relationship between local part temperature gradients with generated residual stress. Using this numerical model, the effects of scan patterns are investigated.  more » « less
Award ID(s):
1657195
NSF-PAR ID:
10055075
Author(s) / Creator(s):
; ; ;
Date Published:
Journal Name:
28th International Solid Freeform Fabrication Symposium - An Additive Manufacturing Conference
Page Range / eLocation ID:
2546-2550
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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    Distortion arises during machining of metallic parts from two main mechanisms: 1) release of bulk residual stress (BRS) in the pre-form, and 2) permanent deformation induced by cut tools. Interaction between these mechanisms is unexplored.

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    Methods

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    Results

    Milling in samples with high BRS magnitude changes the directions of MIRS and distortion relative to the milling direction, with the direction of maximum curvature rotating toward or away from the milling direction depending on the sign and direction of BRS. High magnitude BRS was also found to increase the wafer peak arc height, nearly doubling the amount found in low BRS samples.

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    Measured residual stress and observed wafer distortion both show interactions between MIRS and BRS. Stress analysis models show that the differences in measured MIRS are consistent with the differences in observed distortion.

     
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