The family of additive manufacturing techniques has been attracting significant attention of manufacturers and researchers, due to its unrivalled flexibility to fabricate and repair geometrically complex objects. However, material shaping is not sufficient: wide adoption of additive manufacturing can only occur upon the achievement of satisfactory mechanical performance in terms of structural integrity. The present study exploits a wide range of micro-scale experimental techniques to shed light on fatigue failure mechanisms of Laser Metal Deposition IN718 Ni-base superalloy, and to study the effect of shot peening treatment. Thorough microstructural and fractographic analyses revealed the main deformation mechanism associated with twinning during crack propagation, while crack initiation was found to be promoted by both slip system deformation and twinning around microstructural defects, rather than at sample free-surfaces. It was found that precipitates played a major role in determining the deformation mode. It was discovered that in this case-study, shot-peening residual stresses may have a detrimental effect, in view of the presence of the largest defects within a region where tensile residual stress was present. The results presented here improve understanding of failure mechanisms and thus define future directions of development for manufacture optimisation.
- Additive manufacturing
- Direct energy deposition
- Residual stress
ASJC Scopus subject areas
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering
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- Department of Mechanical Engineering - Senior Lecturer
- Centre for Integrated Materials, Processes & Structures (IMPS)
- EPSRC Centre for Doctoral Training in Advanced Automotive Propulsion Systems (AAPS CDT)
- Institute for Advanced Automotive Propulsion Systems (IAAPS)
Person: Research & Teaching, Core staff, Affiliate staff