Fatigue crack growth tests are conducted to assess the efficacy of the stop-hole crack repair method. This straightforward and widely adopted technique involves drilling a hole at the crack tip and subsequently enlarging it using a pin inserted into the hole. A fracture mechanics-based model is proposed to estimate the extension of fatigue life achieved through the implementation of the stop-hole technique. The model’s predictions are validated using data obtained from fatigue crack growth tests conducted on both unrepaired and repaired M(T) specimens, following the guidelines outlined in the ASTM E647 standard. The error of the fracture mechanics-based model was 1.4% in comparison with the fatigue tests.

Additive manufacturing through laser powder bed fusion (LPBF) has evolved into a key manufacturing process, but machining is still crucial to improve part quality. Holes in LPBF parts present poor accuracy, and helical milling with conventional endmills can be a suitable operation to finish holes in printed metal parts. Due to its superior properties, Inconel 718 is widely applied in aero-engine parts, requiring high reliability. However, Inconel 718 presents a tendency of machining hardening, being classified as a difficult-to-machine material. This work investigates the finishing through helical milling of holes in parts of Inconel 718 obtained through LPBF. LPBF parts of Inconel 718 were obtained with pre-holes and these were finished through helical milling. Holes of LPBF parts may present significant geometrical error. The results indicate that helical milling is suitable for improving the quality of LPBF holes. LPBF parts obtained with the laser scan angle of 67 $$^{\circ }$$ ∘ with thermal treatment presented higher grain refinement and precipitates, resulting in the highest cutting forces and roughness. Cutting force patterns presented a significant correlation with geometrical error variation. Process modeling highlighted the most influential LPBF and helical milling parameters on cutting forces and roughness. The axial and tangential feeds presented directly and inversely proportional effects on cutting forces, respecting the kinematics and undeformed chip volumes. Finally, bi-objective optimization was performed to guide the choice of the best conditions to achieve improved roughness and lowest cutting forces.