研究目的
Investigating the fatigue behaviour of an AlSi10Mg alloy processed by laser powder bed fusion (L-PBF) and subjected to different surface finishing processes, with a focus on the residual defects on the surface and the dominant fatigue failure mechanisms.
研究成果
The study concluded that the fatigue performance of the AlSi10Mg alloy processed by L-PBF is significantly affected by residual defects on the surface and subsurface layers. The fatigue limit was found to be 195 MPa for machined and polished samples, achieved by substantial removal of surface and subsurface defects. The research highlights the importance of evaluating surface and subsurface defects for improved fatigue design of AM parts.
研究不足
The study acknowledges the presence of both internal and surface-related defects in AM products, which can affect fatigue properties. The statistical variability is amplified in AM products due to these defects. The research also notes the limitations of surface roughness parameters in providing a direct and reliable correlation with fatigue strength.
1：Experimental Design and Method Selection
The study involved the fabrication of AlSi10Mg alloy samples using an EOS M290 L-PBF system, followed by different surface finishing processes including sandblasting, vibro-finishing, and machining followed by polishing. The fatigue behaviour was investigated through uniaxial fatigue tests in load-controlled mode.
2：Sample Selection and Data Sources
Samples were produced using a stripe scanning strategy with the scanning direction rotated by 67° after completion of each layer. Three sets of specimens were selected randomly for the fatigue investigation.
3：List of Experimental Equipment and Materials
Equipment used included an EOS M290 L-PBF system, Zeiss EVO 50 EP scanning electron microscope, Nikon Eclipse LV150NL optical microscope, Olympus LEXT OLS4100 confocal microscope, and an MTS Servohydraulic testing frame.
4：Experimental Procedures and Operational Workflow
The process involved L-PBF processing, microstructure analysis, tensile tests, surface finishing, surface characterization, and fatigue testing. Surface texture measurements were performed using confocal microscopy, and nano-indentation measurements were conducted to investigate surface and subsurface hardness profiles.
5：Data Analysis Methods
Data were statistically analyzed according to ISO 12107:2012 standard. The fatigue limit was statistically calculated considering at least 12 specimens per batch. Fracture surfaces were analyzed by SEM to identify nucleation sites and microstructural mechanisms leading to final fracture.
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