Investigation on the fatigue strength of threaded titanium bolts

Extending the service life of mechanical components is a key strategy for enhancing sustainability. This study investigates the fatigue strength of M12 threads manufactured from the titanium aluminium 6 vanadium 4 alloy. Double‐threaded cylindrical specimens and a newly developed holder design were used to investigate the fatigue strength in the finite life time regime. Stress‐controlled cyclic fatigue tests were conducted at room temperature with a constant stress ratio of R = 0.3 in accordance with relevant standards. Quasi‐static tensile testing were done to determine the mechanical properties and metallographic analyses using Kroll, Weck and thermochemical etching were performed to investigate the microstructure. The results reveal significant scatter in fatigue life exceeding one order of magnitude, while metallography shows a predominantly equiaxed α phase microstructure with intergranular β phase and no observable deformation induced by thread cutting.