Kerstin Winkler

This study quantifies the mechanical degradation caused by locally introduced rubber-glove contamination in stress-relieved PBF-LB/M Ti-6Al-4V. Rubber-glove fragments were inserted into defined build layers of standardized tensile specimens and into highly loaded transition regions of a topology-optimized bracket demonstrator. Twelve uncontaminated and twelve contaminated tensile specimens and nine brackets per condition were evaluated. The contaminated tensile specimens exhibited a mean ultimate strength of approx. 860 MPa compared with approx. 1200 MPa for the reference condition, corresponding to a reduction of approx. 28%. Mean elongation at break decreased from approx. 13.4% to 0.6%, representing a reduction of approx. 95%. Fracture preferentially occurred at the contamination insertion region and was associated with planar fracture features and retained spherical powder particles. The results support a predominantly defect-controlled degradation mechanism associated with locally disturbed consolidation.

In this study, the Ti-6Al-4V powder material for additive manufacturing was mixed with amorphous carbon and processed by powder bed fusion using a laser beam. The specimens were subjected to mechanical and microstructural analyses to investigate the impact of the organic constituent that may become introduced unintentionally as an impurity along the powder handling chain. It is documented that hardness and tensile strength increase with increasing carbon content up to 0.2 wt.%. Above this carbon concentration, extensive crack formation in the samples prevents successful procession.