Deformation behaviour of additively manufactured microlattice structures : a micro-structural investigation

The aim of this research is to characterize the thin strut members that constitute metallic microlattice materials, which might be subjected to size effect phenomena and in turn would affect the performance of bulk structures. Samples manufactured by laser Powder Bed Fusion (PBF) process using 316L stainless steel were used as the candidate microlattice material, and detailed material characterization revealed both internal and external structure to be marred with defects ranging from bulk to nano-scale, originated from rapid solidification during manufacturing. Single-crystal tensile tests were conducted to obtain mechanical response free of the effect of voids that are characteristic by-product of PBF process, and a framework to obtain poly-crystal response considering size effect was formulated based on dislocation mediated plasticity theory. The validity of the proposed framework was verified against experimental result by multiscale simulation where the stochastic voids distribution was considered. The establishment of the size-dependent characterization framework explained the age old anomaly of bilinear Hall-Petch relationships caused by size-effect in 316L stainless steel. The resulting defects in PBF process and the exhibition of unusually high strength-ductility property were possible to explain through the melt pool thermodynamics, that puts laser PBF produced 316L stainless steel to be high performing than most common engineering materials and comparable to high strength steels.

Grantor dc:publisher

UNSW, Sydney

Year dc:date

2019

Author dc:creator

• Rashed, Md Golam

• Metallic microlattice
• Additive manufacturing
• Selective laser melting
• Size effects
• Multiscale modeling

Statement dc:rights

• open access
• CC BY-NC-ND 3.0
• free_to_read

Licence

• https://purl.org/coar/access_right/c_abf2
• https://creativecommons.org/licenses/by-nc-nd/3.0/au/

Language dc:language

EN

Identifier

https://doi.org/10.26190/unsworks/3860

OAI identifier oai:identifier

oai:unsworks.library.unsw.edu.au:1959.4/64589