扫描策略对HTSLM制备316L/IN718梯度材料组织性能的影响

Effect of scanning strategy on microstructure properties of 316L/IN718 gradient materials prepared by HTSLM

随着现代工业对高性能材料的需求日益增长,功能梯度材料(FGM)因其在不同区域具有不同性能的特点而受到广泛关注。镍铁基FGM因其优异的高/低温复合综合力学性能和耐腐蚀性,在航空航天、石油化工等领域具有重要应用前景。传统制造方法在制造FGM方面的局限性限制了其应用,而增材制造技术可制造高度复杂的零件,同时降低损耗,为制造复杂的FGM结构奠定了基础。通过高通量选区激光熔化设备(HTSLM)研究了扫描策略(扫描方式、不同搭接率)对316L/IN718功能梯度材料的成形件孔隙、微观组织和力学性能的影响规律,研究结果表明,扫描方式对316L/IN718功能梯度材料的影响要大于搭接率,条带状扫描方式、扫描间距等于激光光斑直径的工艺参数成形的316L/IN718功能梯度材料的抗拉强度和屈服强度最高,分别为854 MPa和676 MPa。随着IN718含量减少,微观组织以Laves相为主的柱状晶减少,梯度材料的显微硬度线性降低,Ni、Nb、Mo固溶增量的降低是导致显微硬度降低的主要原因,而成分变化过快和Laves相的存在是导致界面结合性能差和裂纹形成的重要原因。研究结果有助于选择合适的扫描策略,了解高通量选区激光熔化制造功能梯度材料的成形机理,对比不同扫描方式和搭接率下316L/IN718 FGM的微观组织和力学性能,旨在为制造高品质的功能梯度材料提供有益的指导和参考。

With the increasing demand for high-performance materials in modern industry,functionally graded materials(FGM)have attracted extensive attention due to their characteristics of different properties in different regions.Nickel-iron-based FGM has important application prospects in aerospace,petrochemical and other fields due to its excellent high/low temperature composite comprehensive mechanical properties and corrosion resistance.While the limitations of traditional manufacturing methods in manufacturing FGMs limit their application,additive manufacturing techniques provide the foundation for fabricating complex FGM structures by manufacturing highly complex parts with reduced losses.The effects of scanning strategies(scanning methods,different lap ratios)on the porosity,microstructure and mechanical properties of 316L/IN718 functionally graded materials were studied by highthroughput selective laser melting equipment(HTSLM),and The results show that the influence of the scanning method on the 316L/IN718 functional gradient material is greater than the lap rate,and the tensile strength and yield strength of 316L/IN718 functional gradient material formed by strip scanning method and scanning spacing equal to laser spot diameter were the highest,which were 854 MPa and 676 MPa,respectively.With the decrease of IN718 content,the columnar grains dominated by Laves phase in the microstructure decreased,the microhardness of the gradient material decreased linearly,and the decrease of Ni,Nb and Mo solution increment is the main reason for the decrease of microhardness,while the rapid change of composition and the existence of Laves phase were important reasons for poor interfacial bonding performance and crack formation.The results of this study will help to select appropriate scanning strategies,understand the forming mechanism of high-throughput selective laser melting to fabricate functionally graded materials,and compare the microstructure and mechanical properties of 316L/IN718 FGM under different scanning methods and lap ratios,aiming to provide useful guidance and reference for the fabrication of high-quality functional-graded materials.