Effect of the Boundary Orientation of Melt Pool on Mechanical Property and Fracture Path in Selective-Laser-Melted AlSi10Mg Alloy

The present work investigated the effect of the boundary orientation of melt pool on the mechanical properties and fracture path in selective-laser-melted AlSi10Mg alloy. The acquired data are beneficial for understanding the influence of the microstructure on mechanical properties. During the alloy’s selective laser melting (SLM), the melt pool boundary was almost parallel with the scanning direction, and the grains grew along the building direction. When the load-bearing face was perpendicular to the melt pool boundary, the crack propagation path deflected towards coarse melt pool of the melt pool boundary, reducing the probability of directly crossing the fine melt pool. Otherwise, the cracks would mainly propagate along the melt pool boundary. In the tensile deformation process, coarse melt pool (CMP) was subjected to higher local strain than fine melt pool (FMP) and heat-affected zone (HAZ), and the crack propagated or deflected along the CMP in the melt pool boundary. Therefore, the anisotropy of mechanical properties in SLM AlSi10Mg was mainly ascribed to the CMP density on the load-bearing face. As a weak area, the high proportion of CMP significantly reduced the strength and plasticity of the alloy.

In order to investigate the anisotropy of mechanical properties of SLM AlSi10Mg, the damage mechanism and fracture behavior of transverse and longitudinal specimens were studied. CMP of the melt pool boundary is the weak zone. Then the schematic illustration for the crack propagation was made according to experiment results.