Overcoming the strength-ductility trade-off in additive manufactured AlSi10Mg plates by friction stir welding at a low rotational speed

The main problem in post-treatment of laser powder bed fusion (L-PBF) AlSi10Mg is the sharp reduction in strength when the ductility enhances, i.e. the problem of strength -ductility trade-off. Friction stir welding (FSW) at a low rotational speed of 200 rpm was employed to join AlSi10Mg plate produced by laser-powder bed fusion in conjunction with overcoming the strength-ductility trade-off. The microstructure, texture, and mechanical properties of the as-built and friction stir welded samples were examined. FSW resulted in the elimination of porosities, formation of ultrafine-grains with an average grain size of 0.7 mm, increment in dislocation density and Taylor factor, and fragmentation of Si parti-cles. In addition, after FSW, B=B and C shear texture components were mainly formed in the center of the stir zone, while at the shoulder-dominated zone the A*1(111)[112] and A*2(111)[112] components might be formed. The main grain structure formation mecha-nism was continuous dynamic recrystallization occurring by a gradual increase in misorientation of low angle grain boundaries and geometrically dynamic recrystallization. Consequently, tensile elongation was enhanced by =173%, while a negligible decrease in strength (=9%) was observed. During tensile loading, the joint was fractured from the stir zone by the initiation of cracks from the surface of the sample, resulting in a bimodal dimple structure.(c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Automated summary

The main problem in post-treatment of laser powder bed fusion (L-PBF) AlSi10Mg is the strength-ductility trade-off. Friction stir welding (FSW) was used to join AlSi10Mg plate produced by L-PBF and overcome this trade-off. FSW resulted in improved microstructure, texture, and mechanical properties. Tensile elongation was enhanced by 173% with a negligible decrease in strength (9%). The joint fractured from the stir zone during tensile loading, forming a bimodal dimple structure.