研究目的
To evaluate the influence of defects on the fatigue strength and life of SLM processed Ti-6Al-4V alloy within the framework of defect-tolerant design.
研究成果
The study concludes that the combination of X-ray tomography and the statistic of extremes can provide a conservative defect size for subsequent fatigue strength evaluation. The extended Kitagawa-Takahashi diagram considers not only the safe-life regime determined by the Chapetti model but the defect-determined residual lifetime within the finite life regime.
研究不足
The study acknowledges the challenge of effectively controlling large-sized defects, especially for lack of fusion defects, by parameter optimization or process promotion in SLM processing.
1：Experimental Design and Method Selection:
The study involved a thorough testing procedure including assessment of the microstructure, defect population, tensile strength, microhardness, fatigue crack growth (FCG) rate and fatigue limit via a combination of optical microscopy (OM), electron backscattered diffraction (EBSD), synchrotron radiation X-ray micro computed tomography (SR-μCT) and material testing.
2：Sample Selection and Data Sources:
Ti-6Al-4V powder was used to produce vertically built cylindrical parts using a commercial EOS-M280 manufacturing system.
3：List of Experimental Equipment and Materials:
Equipment included a TESCAN GAIA3 scanning electron microscope (SEM), an HVS-30 Vickers tester, an MTS Bionix858 servo-hydraulic system, and a QBG-100 high frequency testing machine.
4：Experimental Procedures and Operational Workflow:
The process involved microstructural examination, X-ray computed tomography, mechanical behavior testing, and fatigue resistance testing.
5：Data Analysis Methods:
The fatigue strength was evaluated in terms of the defect population using a combination of the statistics of extremes and the Murakami model.
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