## 5 Conclusions  
The study presented establishes clear, experimentally measured differences in the fracture behavior of Ti-6 Al-7 Nb produced via a conventional drawing process compared to selective laser melting.  
The threshold stress intensity factor measurements revealed that the SLM-produced specimens exhibited a higher initial resistance to crack initiation, with \(\Delta K_{\text{th}}\) = 4.53 MPam\({}^{0.5}\), compared to the drawn specimens, with \(\Delta K_{\text{th}}\) = 3.84 MPam\({}^{0.5}\). However, this was contradicted by different fracture toughness values, where the drawn alloy demonstrated higher \(K_{\text{c}}\) = 84 MPam\({}^{0.5}\) compared to the SLM-produced specimens, with \(K_{\text{c}}\) = 21.9 MPam\({}^{0.5}\).  
Analysis of crack growth under cyclic loading revealed further distinctions. The drawn alloy followed Paris' law, with parameters C = 8.555 \(\times\) 10\({}^{-14}\) and m = 5.077, while the SLM-produced alloy showed C = 7.199 \(\times\) 10\({}^{-12}\) and m = 4.6. This indicates that the crack propagation in the SLM parts occurs significantly faster in the low-\(\Delta\)K regime, a difference mainly attributed to the microstructural non-uniformity and higher porosity inherent to the production process. In contrast, the drawn material's more homogeneous structure slows initial crack growth but increases its sensitivity to load increases, as indicated by the higher exponent m. Supporting these quantitative findings, resistance curve behavior further supported the differences between the production processes. The drawn specimens displayed stable and rising J-R and CTOD-R curves, typical for ductile fracture and stable crack growth. In contrast, the SLM specimens exhibited highly brittle behavior, leading to crack instability that resulted in significant data scattering and prevented the collection of reliable crack extension measurements necessary for constructing a valid J-R curve.  
Fracture toughness determination using cylindrical test specimens confirmed the fundamental trend observed, with rectangular specimens showing higher values in the drawn rod specimens compared to the SLM-produced specimens. While the absolute values differed slightly between the two testing methods, both experiments confirmed that traditional manufacturing yields superior fracture resistance in Ti-6 Al-7 Nb.  
The comprehensive data supplied here, including explicit Paris' law parameters and experimentally determined toughness values, enables more accurate service-life prediction and provides a foundation for rational selection between conventional and additive production for biomedical and structural applications.  
Conceptualization, D.K. and N.G.; methodology, D.K. and I.G.; validation, T.V., N.G. and I.G.; investigation, I.G.; data curation, T.V.; writing--original draft preparation, I.G.; writing--review and editing, P.K. and M.K.; visualization, I.G.; supervision, P.K. and M.K. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
Dataset available on request from the authors.  
The research was performed with the equipment of the Fakulteta za Strojnistvo Univerze v Mariboru, to whom the authors extend their gratitude.  
The authors declare no conflicts of interest.  
The following abbreviations are used in this manuscript:  
\begin{tabular}{l l} SLM & Selective Laser Melting \\ AM & Additive Manufacturing \\ ISO & International Organization for Standardization \\ ASTM & American Society for Testing and Materials \\ CMD & Crack Mouth Opening Displacement \\ LLD & Load Line Displacement \\ SEN & Scanning Electron Microscopy \\ \end{tabular}