激光粉末床熔融( Laser Powder Bed Fusion,LPBF)技术具有复杂结构快速成形的显著优势,在诸多领域应用广泛.然而,LPBF复杂的工艺特点使其成形件易出现气孔和未熔合等孔隙缺陷.针对航空航天、船舶和能源等领域广泛应用的Inconel 718合金,开展了激光粉末床熔融实验与数值模拟研究.分析了激光功率、扫描间距和扫描速度等关键工艺参数对成形缺陷的影响,结合实验检测与离散元模拟,讨论了气孔和未熔合等孔隙缺陷的产生机制.研究结果表明:当激光扫描间距减小时,试样纵截面孔隙率降低;激光扫描速度增加时,试样边缘未熔合缺陷增加;激光功率增加时,试样内部气孔数量显著减少,同时在熔道边缘出现不规则未熔合缺陷.在激光扫描间距为80 μm、激光扫描速度为500 mm/s、激光功率为200 W时,可以得到熔道宽度合适,试样成形缺陷较少、孔隙率较低的试样.
Effect of LPBF process parameters on forming defects of Inconel 718 alloy
Laser Powder Bed Fusion (LPBF) technology has significant advantages in rapid prototyping of com-plex structures and is widely used in many fields. However,the complex process characteristics of LPBF make its formed parts prone to pore defects such as porosity and lack of fusion. Laser powder bed melting experiments and numerical simulations were conducted on Inconel 718 alloy which was widely used in aerospace,shipbuild-ing,and energy fields. This article combined experimental forming and numerical simulation methods to conduct research. The discrete element method was used to establish a random powder bed model,and the dynamic flow evolution process of the LPBF melt pool was simulated through computational fluid dynamics methods. This arti-cle analyzed the influence of key process parameters such as laser power,scanning spacing,and scanning speed on forming defects. Combining experimental detection and discrete element simulation,the mechanism of pore defects such as porosity and lack of fusion was discussed,and the optimal process parameter data was obtained through analysis.When the laser scanning spacing decreases,the porosity of the longitudinal section of the sample decreases. When the laser scanning speed increases,the number of non fusion defects at the edges of the sample increases. When the laser power increases,the number of pores inside the sample significantly decreases,and ir-regular non fusion defects appear at the edge of the melt. At a laser scanning interval of 80 μm. When the laser scanning speed is 500 mm/s and the laser power is 200 W,a sample with appropriate melt width,fewer forming defects,and lower porosity can be obtained.
Laser Powder Bed FusionInconel 718 alloyprocess parameterspore defectdiscrete element simu-lation
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