Dynamic loading of direct metal laser sintered AlSi10Mg alloy: Strengthening behavior in different building directions

Abstract

Rod shaped samples of AlSi10Mg alloy were additively manufactured in vertical and horizontal directions using direct metal laser sintering technique and subjected to dynamic loading using Split Hopkinson Pressure Bar apparatus at a strain rate of 1400 s−1. Despite employing the same process parameters to fabricate the samples in two directions, the as-built samples possessed different microstructures, where columnar and equiaxed microstructures were developed in the vertical and horizontal samples, respectively. Moreover, fine and coherent Si precipitates were observed in the vertical sample while coarse and semi-coherent ones were developed in the horizontal sample. In addition, changing the building direction from horizontal to vertical led to a three-fold increase in dislocation density. After applying the compressive impact loads on the vertical and horizontal samples, it was found that the dynamic loading behavior of the two samples was almost similar despite the crucial differences in the initial microstructures. The microstructural analysis of the deformed samples revealed entangled networks of dislocations. In addition, over some locations, low angle grain boundaries developed due to partial dynamic recovery. The strengthening behaviors of the two samples additively manufactured in vertical and horizontal directions were investigated using the fundamentals of alloy hardening to unveil the similarities.