Influence of tool rotational speed on the microstructural characterization and mechanical properties of friction stir welded Al-Si10Mg parts produced by DMLS additive manufacturing process

[Display omitted] •Tool rotational speed on microstructural and mechanical properties of AM-DMLS AlSi10Mg alloy has been investigated.•AlSi10Mg alloy exhibits a crescent shape microstructure consist of equiaxed dendritic structure with fine grains of eutectic mixture.•Profound examination of stir zone of the welded joints by EBSD shows maximum grain refinement at low rotational speed.•Tensile properties and microhardness study has been carried out. Present study investigate the joining of precipitation hardened AlSi10Mg alloy, developed using direct metal laser sintering technique of additive manufacturing using friction stir welding. Consequently, three, single-pass, square butt-welded joints were fabricated from 3 mm thick plates of this alloy, using friction stir welding process at different tool rotational speeds (low, medium and high). Each welded joint was fabricated at the same transverse speed of 50 mm/min, H13 tool steel possessing scrolled shoulder and 3° tilt angle. Microstructural observations show a significant grain refinement within the stir zone, which reduced with the increase in tool rotational speed. This variation was accredited to the significant dynamic recrystallization in the weldment, and change in the morphology and size of the Si-particles. The transverse tensile test results show a considerable drop in the joint efficiency of the welds from ≈48% to ≈42% with the increase in tool rotational speed from low to high.