航天运载器大型金属构件激光定向能量沉积研究及应用进展(特邀)

Research and Application Progress of Laser Directed Energy Deposition on Large-scale Metal Components in Aerospace(Invited)

激光定向能量沉积(LDED)增材制造技术由于成形效率高、材料送进方式灵活、成形自由度高等特点,非常契合当前及未来航天装备结构大型化、整体化、轻量化、高精度的发展趋势,并已在运载火箭、载人飞船、火箭发动机等领域实现牵引性应用。总结当前铝合金及其复合材料、钛合金及其复合材料、镍基高温合金及其复合材料等3类航天装备结构主体材料的LDED研究现状,在此基础上,梳理出LDED工艺的发展方向及研究进展。重点介绍航天装备主承力结构、异质合金一体化结构、集成流道整体化结构等3类典型结构LDED制造难点、研制及应用进展。最后,对LDED增材制造技术材料、工艺及装备等的发展方向进行了展望。

Significance Largescale,integrated,lightweight,and highprecision structures are becoming crucial trends in the development of aerospace equipment.Laser directed energy deposition(LDED)technology,with its high forming efficiency,flexible material feeding methods,and extensive freedom in shaping,proves to be highly suitable for the evolving trends in aerospace equipment development.It has gained significant traction in sectors such as launch vehicles,manned spacecraft,and rocket engines,positioning the aerospace industry as a key driver in the development and application of LDED technology.However,the current progress in LDED additive manufacturing technology is not adequately aligned with industry needs.This misalignment leads to underutilization of its technical advantages,vague directions for technological development,and limited application scenarios and fields.To expedite the technology s industrialization and intelligent evolution,and to achieve largescale,systematic applications,it is essential to review and document the current research and application advancements of LDED for largescale metal components in aerospace.This involves examining material research,process development,and application progress,and identifying future directions for LDED technology.Progress In recent years,significant breakthroughs have been made in the LDED process for aluminum alloys,titanium alloys,nickelbased superalloys,and their composites.The introduction of rare earth elements,such as Sc and Zr,for microalloying modifications and the addition of nanoparticles address challenges such as hot cracking,excessive defects,and the limitations of a single strengthening mechanism that leads to insufficient performance in aluminum alloys.This advancement enables the preparation of various highdensity and highperformance aluminum alloy materials,including AlMnSc,TiB2/AlMgScZr,and 6061-RAM2.Additionally,the development of a range of titanium alloys and their composites suitable for the LDED process,such as TiCu,TiOFe,and TiB/TC4,eliminates coarse columnar crystal structures in favor of uniform and fine equiaxed crystal structures.This development is expected to address the longstanding challenge of performance anisotropy in additive manufacturing titanium alloys.Issues such as the suppression of solidification and liquation cracks,microstructure refinement,uniformity improvement,and performance enhancement in nickelbased/nickelironbased superalloys,including IN 718,IN 625,and HR1,have been resolved.These solutions lead to a significant performance improvement in the prepared materials,with the IN 718 and IN 625 superalloys achieving performance levels comparable to forged materials of the same grade.This paper first summarizes the current research status of LDED technology applied to three primary structural materials in aerospace equipment.Currently,the LDED process for metal materials faces challenges such as hardtomanage defects,uneven microstructures,insufficient strength and toughness,low manufacturing efficiency,and poor surface quality.In response,researchers domestically and internationally have developed various new highperformance,highefficiency,and highprecision LDED processes aimed at enhancing performance,deposition efficiency,and manufacturing accuracy.By employing external fields such as acoustic,deformation,and magnetic fields to assist LDED,significant strides have been made in eliminating defects,refining microstructures,and improving performance.The development of laser processing heads with high deposition rates,multichannel deposition equipment,and processes have boosted deposition efficiency.Additionally,the creation of highprecision powder feeding nozzles and additivesubtractive hybrid manufacturing equipment and processes has enhanced the quality of deposited surfaces.Notably,the Fraunhofer Institute for Laser Technology s development of threedimensional EHLA technology has achieved manufacturing accuracy of up to 100µm and a deposition efficiency of up to 532 cm3/h,setting a benchmark for the future direction of LDED technology.As LDED processes for aluminum alloys,titanium alloys,nickelbased superalloys,and their composites mature and stabilize,alongside the development of new,highperformance,highefficiency,and highprecision processes,LDED technology has realized significant applications in aerospace.This includes use in critical areas,such as launch vehicles and manned spacecraft s main loadbearing components,as well as in the manufacturing of copper alloy/superalloy heterogeneous alloy combustion chambers and integrated nozzles for rocket engines.The aerospace industry s demand for lightweight,integrated,hightemperatureresistant,and highprecision equipment has propelled the development and industrial application of LDED technology.Conclusions and Prospects This paper first summarizes the current research status of LDED technology applied to three primary structural materials in aerospace equipment: aluminum alloy, titanium alloy, nickelbasedsuperalloy, and their composites. Building on this foundation, it organizes the development directions and research progress of LDED processes. It then delves into the manufacturing challenges, research, and application advancements of three typical aerospace equipment structures: the main loadbearingstructure, the integrated structure of heterogeneous alloy, and the integrated structure with integrated flow channels. Lastly, the paper forecasts the development trajectory of materials, processes, and equipment for LDED additive manufacturing technology, highlighting the following strategic directions: the promotion of dedicated highperformancealloy materials design and development, tailored to the unique nonequilibrium physical metallurgy characteristics of the LDED process;the acceleration of highprecisionLDED process, equipment, and software research and development, including the highprecisionformation of large complex structures;the advancement of additive and subtractive hybrid manufacturing technology research;and the hastening of lowcostLDED manufacturing technology development.