Development of macro-defect-free PBF-EB-processed Ti-6Al-4V alloys with superior plasticity using PREP-synthesized powder and machine learning-assisted process optimization

The elimination of internal macro-defects is a key issue in Ti-6Al-4V alloys fabricated via powder bed fusion using electron beams (PBF-EB), wherein internal macro-defects mainly originate from the virgin powder and inappropriate printing parameters. This study compares different types powders by combining support vector machine techniques to determine the most suitable powder for PBF-EB and to predict the processing window for the printing parameters without internal macro-defects. The results show that powders fabricated via plasma rotating electrode process have the best sphericity, flowability, and minimal porosity and are most suitable for printing. Surface roughness criterion was also applied to determine the quality of the even surfaces, and support vector machine was used to construct processing maps capable of predicting a wide range of four-dimensional printing parameters to obtain macro-defect-free samples, offering the possibility of subsequent development of Ti-6Al-4V alloys with excellent properties. The macro-defect-free samples exhibited good elongation, with the best overall mechanical properties being the ultimate tensile strength and elongation of 934.7 MPa and 24.3%, respectively. The elongation of the three macro-defect-free samples was much higher than that previously reported for additively manufactured Ti-6Al-4V alloys. The high elongation of the samples in this work is mainly attributed to the elimination of internal macro-defects.

Automated summary

In this study, different types of powders were compared using support vector machine techniques to determine the most suitable powder for Ti-6Al-4V alloys fabricated via powder bed fusion using electron beams. The results showed that powders fabricated via plasma rotating electrode process had the best properties and were most suitable for printing. A processing map was constructed using support vector machine to predict a wide range of printing parameters for obtaining macro-defect-free samples. The macro-defect-free samples exhibited good elongation and excellent mechanical properties.