1 COMAC Shanghai Aircraft Design and Research Institute, Shanghai 201210, China 2 State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China 3 Xi'an Space Engine Company Limited, Xi'an 710000, China
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.
Fig.6 SLM成形AlSi10Mg合金在不同退火时间下的低倍(1)、高倍(2)微观组织图及Si颗粒尺寸分布(3)(T=300 ℃) (a)5 min;(b)15 min;(c)30 min;(d)60 min;(e)120 min
Fig.7 SLM成形AlSi10Mg合金在不同退火时间下的低倍(1)、高倍(2)微观组织图及Si颗粒尺寸分布(3)(T=500 ℃) (a)5 min;(b)15 min;(c)30 min;(d)60 min;(e)120 min
Fig.8 退火过程中共晶组织形貌演化示意图
State
Ultimate tensile strength/MPa
Yield strength/MPa
Elongation/ %
As-deposited
398.5±11.5
264.5±3.5
4.3±0.2
300 ℃×60 min
287.0±5
176.5±0.5
10.3±0.7
500 ℃×60 min
268.0±2
146.5±1.5
17.2±0.3
Table 3 激光选区熔化成形AlSi10M合金在不同退火温度下的力学性能
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