| About this Abstract |
| Meeting |
10th International Symposium on Superalloy 718 and Derivatives (2023)
|
| Symposium
|
Superalloy 718 and Derivatives
|
| Presentation Title |
Effects of Scan Strategy Induced Microstructural Differences on Thin-wall SLM IN718 Fatigue Performance |
| Author(s) |
Connor Varney , Imran Noor, Paul Rottmann |
| On-Site Speaker (Planned) |
Connor Varney |
| Abstract Scope |
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 scan strategies. In this study a series of IN718 compact tension fatigue test samples were printed via selective laser melting at 1.25mm in thickness using a contour+hatching scan strategy with both rotating and static beam directions at each build layer with half having the crack oriented parallel and the others perpendicular to the build direction. To quantify the effect of sub-surface porosity on fatigue crack initiation, a selection of the samples had an internal (~0.5mm) pore placed in front of the notch. To investigate the influence of scan strategy on the low-cycle fatigue (LCF) resistance of AM IN718, these samples were LCF tested to failure using a custom micromechanical test setup equipped with piezo actuator and digital image correlation (DIC) to identify the onset of plasticity and the initiation and propagation of fatigue cracks and across 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 microstructural features were characterized utilizing several techniques (SEM, EBSD, microCT) and compared to observations from mechanical testing. |
| Proceedings Inclusion? |
Definite: At-meeting proceedings |