Microstructure, cracking behavior and control of Al-Fe-V-Si alloy produced by selective laser melting

Selective laser melting (SLM) technology based on atomized powder was used to fabricate Al-8.5Fe-1.3V-1.7Si (wt%) alloy parts. The microstructure and crack characterization of SLM samples fabricated at various conditions were presented. Results show that the cracks appear periodically along the building direction, initiate preferably at the outer edges of the as-built samples and propagated along the remelting border zone (RBZ) into deposited layers. Solid-phase cracking is proposed according to the fracture morphology. The thermal-induced residual stress during SLM combined with the precipitation of relatively large-sized AlmFe phase in the RBZ results in the formation of cracks. Enhancing scanning speed and hatch distance enable to reduce the cracking sensitivity. The crack-free Al-8.5Fe-1.3V-1.7Si parts can be fabricated at optimized parameters of laser power of 320 W, scanning speed of 1000 mm center dot s(-1) and hatch distance of 0.10 mm along with proper laser pre-heating procedure. The samples built horizontally show good ultimate tensile properties of 454 MPa in average with the elongation of 7.2%.

Automated summary

Selective laser melting (SLM) technology using atomized powder was utilized to fabricate Al-8.5Fe-1.3V-1.7Si alloy parts. Cracks were observed periodically along the building direction and primarily initiated at the outer edges of the samples. Solid-phase cracking was proposed as the mechanism based on fracture morphology. Thermal-induced residual stress and precipitation of large-sized AlmFe phase in the remelting border zone (RBZ) were identified as the causes of cracking. Increasing scanning speed and hatch distance reduced cracking sensitivity. Crack-free Al-8.5Fe-1.3V-1.7Si parts were successfully fabricated using optimized parameters and showed good ultimate tensile properties with an average strength of 454 MPa and elongation of 7.2%.