Effects of Scan Strategy Induced Microstructural Differences on Thin-Wall SLM IN718 Fatigue Performance

Tracy Connor Varney, Md Imran Noor, Paul F. Rottmann

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


The as-printed microstructure of additively manufactured parts is a function of many variables that span from scan strategy to part geometry. This is particularly relevant in precipitation strengthened alloys (e.g. IN718), as thermal history—which itself varies across a build—dictates the distribution of precipitates in the microstructure. Elucidation of the complex relationship between geometry, scan strategy, and resultant microstructure is necessary to optimize future scan strategies. In this study, a series of IN718 dogbone samples were printed via selective laser melting at 0.8 mm in thickness using a contour + hatching scan strategy with both rotating (67°) and static beam directions. To quantify the effect of subsurface porosity on fatigue crack initiation, the as-built surface was left intact on the thinwall samples. As a reference, a 10 mm thick “bulk” sample was also printed and had 0.8 mm thick dogbones removed from it. To investigate the influence of scan strategy on the low-cycle fatigue (LCF) resistance of AM IN718, these samples were tested to failure using a custom micromechanical test setup equipped with a linear actuator and digital image correlation (DIC) to identify the onset of plasticity and the initiation and propagation of fatigue cracks across the sample surfaces. The driving hypothesis for this study is that the rotated scan strategy increases the fatigue resistance due to a more uniform microstructure with smaller grains. As-printed defects and fracture surfaces were characterized utilizing SEM imaging and DIC analysis and compared to observations from mechanical testing.

Original languageEnglish
Title of host publicationProceedings of the 10th International Symposium on Superalloy 718 and Derivatives, 2023
EditorsEric A. Ott, Joel Andersson, Chantal Sudbrack, Zhongnan Bi, Kevin Bockenstedt, Ian Dempster, Michael Fahrmann, Paul Jablonski, Michael Kirka, Xingbo Liu, Daisuke Nagahama, Tim Smith, Martin Stockinger, Andrew Wessman
Number of pages16
StatePublished - 2023
Event10th International Symposium on Superalloy 718 and Derivatives, 2023 - San Diego, United States
Duration: Mar 19 2023Mar 23 2023

Publication series

NameMinerals, Metals and Materials Series
ISSN (Print)2367-1181
ISSN (Electronic)2367-1696


Conference10th International Symposium on Superalloy 718 and Derivatives, 2023
Country/TerritoryUnited States
CitySan Diego

Bibliographical note

Publisher Copyright:
© 2023, The Minerals, Metals & Materials Society.


  • Additive manufacturing
  • Fatigue performance
  • IN718

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy Engineering and Power Technology
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry


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