Investigating the dynamic failure and fragmentation behavior of additively manufactured Ti-6Al-4V with a novel ring expansion methodology.

The potential of additively manufactured (AM) materials in industries including aerospace and defence are vast. Understanding their behaviour under extreme conditions is critical to their effective and safe adoption in dynamic environments. Recreating the extreme states experienced in a controlled and repeatable manner can be challenging, historically relying on large-scale, costly and complex explosively driven experimentation.



Ti-6Al-4V is a widely used engineering alloy where understanding of AM dynamic performance significantly lags quasi-static. This work seeks to address the effects of intrinsic material variations by systematically exploring links between fabrication parameters, component microstructure and the high rate constitutive/failure response.

Utilising a single stage gas gun, a novel ring expansion geometry is used to subject a range of SLM Ti-6Al-4V specimens to strain rates exceeding x10⁴s^-1. This simple experimental methodology allows a uniaxial stress state to be driven into a symmetrically expanding ring, causing it to freely expand under its own inertia. Coupled ultra high speed imaging, velocimetry and soft collection diagnostics allow failure and fragmentation behaviour to be investigated. Microstructural characterisation enables links between failure mechanisms, crystal structure and dynamic response to be compared, quantifying the evolution of strength and ductility under extreme loading.