The effect of heat treatment on the room and high temperature mechanical properties of AlSi10Mg alloy fabricated by selective laser melting

Abstract

The present work demonstrates a novel interpretation of the effect of well-known heat treatments of solutionizing (ST) and solutionizing plus aging (T6) along with a newly-developed direct aging (DA), on the microstructural evolution and corresponding deformation behavior of selectively laser-melted AlSi10Mg alloy. To this end, different heat treatments were employed to not only modify the microstructure but also adjust the defect structure. Furthermore, the monotonically deformed microstructures and the corresponding fractured surface at temperatures of 25 and 200 °C was studied to address the effect of post-processes on the damage mechanism. Surprisingly, it has been understood that the flow responses of the treated microstructures haven't improved as much as it was expected. That is attributed to the deteriorating effect of dissolving the cellular structure along with its considerable impact on trapped gas defect. Furthermore, the melt pool boundaries (MPB) found to be prone to crack nucleation and growth owing to the high connectivity of Si-network and strain localization in heat-treated specimens as well as in As-built ones. Small precipitates from the inner part of the melt pool were likely to agglomerate in the heat-affected zone (HAZ) under the Ostwald ripening mechanism where these primary coarse Si precipitates had existed.

Keywords

• AlSi10Mg
• Additive manufacturing
• Selective laser melting
• Heat treatment
• Mechanical properties
• Damage mechanism