激光选区熔化镍基高温合金GH4169的成形工艺与显微组织研究
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摘要
开展了基于激光选区熔化技术对镍基高温合金GH4169成形工艺的研究。研究了激光扫描速度和激光功率对成形试样组织的影响,及激光加工工艺参数对试样显微组织、致密化行为的影响。结果表明:当激光扫描速度一定,激光功率较低时,熔池的球化效应明显,材料内部形成较多孔洞,致密度较低;随着激光功率的提高,熔池内金属溶液表面张力减小,球化效应明显减弱,致密度随之提高。当激光功率一定,扫描速度较低时,金属溶液补缩能力强,材料组织致密,仅存在少量气孔;随着扫描速度的提高,熔池变窄变浅,相邻熔道及层间材料缺陷明显增多。当激光束能量密度较高时,粉末吸收能量较多,熔池温度高,凝固速率低,易形成粗大的柱状晶。在优化工艺参数下(激光功率335 W、激光扫描速率680 mm/s),成形体的致密度最高(98.7%)。
The research on forming process of Ni-based superalloy GH4169 based on laser selective melting technology was carried out. The influences of scanning speeds and laser powers on the microstructure of the formed sample were studied.The influences of laser process parameters on the microstructure and densification behavior of the alloy were researched. The results show that at a lower laser power and constant laser scanning speed, the balling effect of the molten pool is obvious, and there are many holes formed inside the material, resulting in lower density. With the laser power increasing, the surface tension of the molten metal in the molten pool reduces, and the balling effect is obviously weakened, resulting in the density increasing. At a lower scanning speed and constant laser power, the metal melt has a strong feeding ability and the material structure in dense and there is only a small amount of pores. With the scanning speed increasing, the molten pool bacome narrower and shallower, and the defects of adjacent melt channels and interlayers increase significantly. At a higher laser beam energy density, the powder absorbes more energy, the molten pool temperature is higher, the solidification rate is slower, so that the coarsened columnar crystals are easily formed. The samples manufactured at optimized process parameters(the laser power is 335 W, scanning speed is 680 mm/s) exhibits highest density, reaching 98.7%.
The research on forming process of Ni-based superalloy GH4169 based on laser selective melting technology was carried out. The influences of scanning speeds and laser powers on the microstructure of the formed sample were studied.The influences of laser process parameters on the microstructure and densification behavior of the alloy were researched. The results show that at a lower laser power and constant laser scanning speed, the balling effect of the molten pool is obvious, and there are many holes formed inside the material, resulting in lower density. With the laser power increasing, the surface tension of the molten metal in the molten pool reduces, and the balling effect is obviously weakened, resulting in the density increasing. At a lower scanning speed and constant laser power, the metal melt has a strong feeding ability and the material structure in dense and there is only a small amount of pores. With the scanning speed increasing, the molten pool bacome narrower and shallower, and the defects of adjacent melt channels and interlayers increase significantly. At a higher laser beam energy density, the powder absorbes more energy, the molten pool temperature is higher, the solidification rate is slower, so that the coarsened columnar crystals are easily formed. The samples manufactured at optimized process parameters(the laser power is 335 W, scanning speed is 680 mm/s) exhibits highest density, reaching 98.7%.
引文
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[2]王旭葆,曲波.基于SLM工艺的航空铝合金支架的轻量化设计[J].机械设计,2018,35(10):50-53.
[3]Vandenbroucke B,Kruth J P.Selective laser melting of biocompatible metals for rapid manufacturing of medical parts[J].Rapid Prototyping Journal,2007,13(4):196-203.
[4]Yadroitsev I,Krakhmalev P,Yadroitsava I.Selective laser melting of Ti6Al4V alloy for biomedical applications:Temperature monitoring and microstructural evolution[J].Journal of Alloys and Compounds,2014,583:404-409.
[5]Kelbassa I,Albus P,Dietrich J,et al.Manufacture and repair of aero engine components using laser technology[C]//Pacific International Conference on Applications of Lasers and Optics.LIA,2008(1):208-213.
[6]吴楷,张敬霖,吴滨,等.激光增材制造镍基高温合金研究进展[J].钢铁研究学报,2017,29(12):953-959.
[7]张颖,顾冬冬,沈理达,等.INCONEL系镍基高温合金选区激光熔化增材制造工艺研究[J].电加工与模具,2014(4):38-43.
[8]Wu Weihui,Yang Yongqiang,Huang Yanlu.Direct manufacturing of Cu-based alloy parts by selective laser melting[J].Chinese Optics Letters,2007,54:37-40.
[9]Tolochko N K,Mozzharov S E,Yadroitsev I A,et al.Balling processes during selective laser treatment of powders[J].Rapid Prototyping Journal,2004,10(2):78-87.
[10]Kruth J P,Froyen L,Van Vaerenbergh J,et al.Selective laser melting of iron-based powder[J].Journal of Materials Processing Technology,2004,149(1/3):616-622.
[11]潘爱琼,张辉,王泽敏.选区激光熔化镍基单晶高温合金的熔池显微组织[J].激光与光电子学进展,2017,54(7):229-234.
[12]Liu F,Lin X,Yang G,et al.Microstructure and residual stress of laser rapid formed Inconel 718 nickel-base superalloy[J].Optics&Laser Technology,2011,43(1):208-213.
[13]Jia Qingbo,Gu Dongdong.Selective laser melting additive manufacturing of Inconel 718 superalloy parts:Densification,microstructure and properties[J].Journal of Alloys and Compounds,2014,585:713-721.
[14]闫岸如,杨恬恬,王燕灵,等.变能量激光选区熔化IN718镍基超合金的成形工艺及高温机械性能[J].光学精密工程,2015,23(6):1695-1704.