(华南理工大学 广东省金属新材料制备与成形重点实验室，广州 510640)
摘 要: 利用ProCAST软件对不同壁厚(5~30 mm)阶梯件的充型和凝固过程进行模拟，结合模拟结果进行浇注实验，重点研究壁厚对3D打印砂型铸造Al-7Si-0.4Mg合金的微观组织和力学性能的影响。结果表明：随着壁厚减小，合金中α(Al)的二次枝晶臂间距、共晶硅尺寸以及含Fe相的尺寸均减小；而合金的致密度和拉伸力学性能显著升高。T6态下，合金的最高(壁厚5 mm)抗拉强度为279 MPa，断后伸长率为2.13%。随着壁厚减小，合金的凝固冷却速度增加，组织得到细化，致密度提高，合金的强度和伸长率提高。此外，3D打印砂型铸造的铝合金性能受到砂模粘结剂含量的制约，断后伸长率较低。
关键字: 砂型3D打印；铸造铝合金；ProCAST模拟；组织；力学性能
（Guangdong Provincial Key Laboratory for Processing and Forming of Advanced Merallic Materials, South China University of Technology, Guangzhou 510640, China）
Abstract:ProCAST software was used to simulate the filling and solidification process of step parts with different thicknesses (5-30 mm), and the casting experiment was carried out in combination with the simulation results, the effects of thickness on the microstructure and mechanical properties of 3D printing sand casting Al-7Si-0.4Mg alloy were studied. The results show that, as the wall thickness decreases, the secondary dendrite arm spacing, eutectic silicon size, and Fe-containing phase size of α(Al) in the alloy decrease, while the density and tensile mechanical properties of the alloy increase significantly. In the T6 state, the highest (thickness of 5 mm) tensile strength of the alloy is 279 MPa, and the elongation after break is 2.13%. According to the analysis, as the thickness decreases, the solidification cooling rate of the alloy increases, the microstructure is refined, the density is increased, and the strength and elongation of the alloy are improved. In addition, the properties of 3D printings and casting aluminum are limited by the sand mold binder content, and the elongation is low.
Key words: 3D sand printing; cast aluminum alloy; ProCAST simulation; microstructure; mechanical properties
