薄壁结构铝合金激光粉末沉积工艺及性能研究

Study on Process and Properties of Aluminum Alloy Thin-Walled Structure Part by Laser Powder Deposition

利用激光粉末沉积技术成功制备AlSi10Mg铝合金薄壁件。采用粉末负离焦和增大熔覆间隙停留时间的工艺策略,解决铝合金成形过程中熔覆层边缘粗糙、塌陷的问题,并分析薄壁件扫描和沉积不同成形方向上的显微组织和力学性能。结果表明:单道成形的最佳工艺参数为激光功率密度P=370 W/mm2、扫描速度Vs=1.2 m/min、送粉流量Vf=8.5 g/min。薄壁件边缘塌陷程度随熔覆间隙停留时间增大而减小,随着粉末离焦量增大而增大。薄壁件扫描方向的显微组织为细碎的枝晶和少量的等轴晶,沉积方向为粗大的枝晶。薄壁件扫描方向的硬度可达130 HV,抗拉强度可达280.12 MPa,延伸率为12.12%,明显优于沉积方向。

AlSi10Mg thin-walled parts were formed by laser powder deposition technology. The method of negative defocusing of powder and prolonging the interval time of cyclical cladding process were adopted to solve the problems of rough edge and collapse of cladding layer. The microstructure and mechanical properties of the thin-walled part were analyzed both in the direction of scanning and deposition. The results showed that the optimal process parameters of single-pass cladding were laser power density P=370 W/mm2, scanning speed Vs=1.2 m/min, powder feeding rate Vf=8.5 g/min. The edge collapse of thin-walled parts was improved with prolonging the interval time of cyclical cladding process, but worsened by increasing the powder negative defocusing. The microstructure of the thin-walled parts was mainly fine dendrites and a small amount of equiaxed grains in the scanning direction, but the deposition direction was mainly coarse dendrites. The hardness, tensile strength and elongation of thin-walled parts in scanning direction are 130 HV, 280.12 MPa and 12.12% respectively, which are better than those in deposition direction.