Microstructure and mechanical property of annealing heat treated AlSi10Mg alloy fabricated by selective laser melting

Abstract

AlSi10Mg alloy has excellent characteristics such as high specific strength and good wear resistance. The composition of AlSi10Mg alloy is close to the eutectic point, thus it has good forming property and has been widely used in selective laser melting processing. However, for this moment, only the conventional annealing strategy is employed in the selective laser melted AlSi10Mg component, which greatly limits their further applications. In this work, the effects of several annealing on the microstructure and tensile properties of selective laser melted AlSi10Mg alloys were investigated. The results show that the as-fabricated sample presents a mixed structure of columnar α-Al and eutectic Al-Si structure along building direction, which possesses a strong texture of α-Al 〈100〉. The single molten pool consists of fine grain region, coarse grain region and heat affected region. The as-fabricated sample shows ultimate strength of 389.5 MPa with 4% elongation to failure. During the heat treatment, the eutectic Si is broken and spheroidized along with precipitation of supersaturated Al(Si). When the annealing temperature increases from 200 ℃ to 500 ℃, the silicon particle suffers the Ostwald ripening for size increase of 23 times. The samples heat treated at 300 ℃ and 500 ℃ show the ultimate strength of 287.0 MPa and 268.0 MPa, and elongation of 10.3% and 17.2%, respectively.

Keywords

• selective laser melting
• additive manufacturing
• alsi10mg alloy
• heat treatment
• microstructural evolution