The effect of surface finish on tensile behavior of additively manufactured tensile bars
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Additive Manufacturing (AM) has significantly increased the design freedom available for metal parts. Many novel designs rely on the existence of surfaces that are not accessible and therefore rely on the surface finish of the parts directly from the AM equipment. Work has been performed to characterize the difference between AM, then machined tensile samples and AM tensile samples with an unimproved surface finish. This work utilizes surface analysis, fractography, and finite element analysis (FEA) to expand on this by investigating the effects of the unimproved surfaces on local tensile behavior and fracture mechanics in AM materials. Results show that measurement error in cross-sectional area is the main source of variation between unfinished and machined strength measurements. Results also indicate that a ductile material may demonstrate the same tensile strength regardless of post processing. Fractography shows that stress concentration near the surface of the samples leads to changes in fracture behavior likely explaining the difference in elongation of the samples. Finally, FEA work did not successfully show a difference in fracture initiation, though this is likely due to inaccurate representation of the samples surface.
KeywordsFinite Element Analysis Surface Finish Additive Manufacture Stress Triaxiality Equivalent Plastic Strain
The authors would like to acknowledge the assistance provided for this research by AM equipment technicians Kevin Davis and Justin Tannehill, microscopists Brandon Cox and Diana Goedecke and tensile testing personnel Ed Wenski, Bill Lepley, and Jason Rogers. All data prepared, analyzed, and presented have been developed in a specific context of work and were prepared for internal evaluation and use pursuant to that work authorized under the referenced contract. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government, any agency thereof or Honeywell Federal Manufacturing & Technologies, LLC. This presentation has been authored by Honeywell Federal Manufacturing & Technologies under Contract No. DE-NA0000622 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for the United States Government purposes.
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Conflict of Interest
The authors declare that they have no conflict of interest.
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