Influence of temperature and architecture on the amplitude and frequency of serrations in additively manufactured Inconel718 lattices
摘要
The aim of this work is to investigate the influence of temperature (T) and architecture on the nature (type, amplitude, frequency) of dynamic strain aging (DSA) serrations in Inconel 718 (IN718) additively manufactured (AM) lattices. With that goal, three BCC strut-based structures were fabricated by laser powder bed fusion (LPBF) and they were tested in compression at temperatures ranging from 300 to 600 °C and at an initial strain rate of 10–3 s−1. As in bulk IN718, with increasing T, serrations changed from type A to type C and the serration amplitude increased as dislocations encounter progressively harder obstacles. The serration frequency peaked at intermediate temperatures, where an optimum balance between solute diffusivity and solute mobility is more likely. Type C serrations evolve significantly with strain. At 450 °C, their frequency increases significantly, as increasing numbers of dislocations become trapped by highly mobile solutes. At 600 °C their amplitude increases at constant frequency, revealing a higher accumulation of dislocations at hard obstacles. Finally, the serration amplitude increases with the lattice density as the latter is proportional to the volume fraction of material bearing a sufficient load level. These findings offer valuable insights for the design of architected components intended for elevated-temperature service.
Graphical abstract