Influence of process parameter and strain rate on the dynamic compressive properties of selective laser-melted Ti-6Al-4V alloy

Dynamic compressive mechanical responses of selective laser-melted Ti-6Al-4V alloy were studied in terms of the influences of scanning speed, building angle as well as impacting strain rate. It was found that the ultimate flow stress and energy absorption increased first and then dropped sharply as the scanning speed increased from 1.0 to 1.6 m/s, showing that the sample built at scanning speed of 1.2 m/s possessed the best dynamic mechanical properties. They increased straightly up as the building angle increased from 0° to 90°, but only the sample built at 45° ruptured with shearing fracture pattern. Moreover, the samples exhibited distinct strain rate hardening effect, as the applied strain rate increased from 900 to 2100/s, and the sample ruptured ultimately with mixed ductility/brittle fracture pattern. Volume fraction of LAGBs in samples increased from 9.1 to 18.9% and 21.4% after impacting at strain rates of 900/s and 2100/s, indicating that intenser dislocation was activated at a higher strain rate impacting, this is the main cause of enhancement in strength. This study provided an insight into the influence of high strain rate impact loading on the dynamic mechanical responses of SLMed TC4 alloy, which is conducive to further exploiting the performance potential of the SLMed materials.