Yangtze River Delta G60 laser alliance guide
据悉，美国俄勒冈州立大学、卡耐基梅隆大学及博伊西州立大学的科研人员报道了激光功率和沉积顺序对激光定向能沉积GRCop42-Inconel 625接头组织的影响研究。 研究以“Effect of laser power and deposition sequence on microstructure of GRCop42 - Inconel 625 joints fabricated using laser directed energy deposition”为题发表在《Materials & Design》上。
Research Highlights:
- Inconel 625-GRCop42 joints were fabricated at different laser powers using laser directed energy deposition technology.
-By increasing the laser power of the first layer, a non-porous Inconel 625-GRCop42 joint is manufactured.
- The presence of a liquid miscible gap results in a brittle phase that can easily crack in the GRCop42 and Inconel 625 joints.
- By increasing the laser power, it is possible to reduce the volume fraction of the brittle phase in the seam.
Keywords: Inconel 625;GRCop; microstructure; dissimilar metal joints; Laser directed energy deposition.
Thermal management of high-temperature components such as rocket combustion chambers requires the use of additive manufacturing technology to connect Inconel 625 and GRCop42. Although laser directed energy deposition has been previously attempted to join these materials, the effects of laser power and deposition sequence on the microstructure of these joints are poorly understood. In this study, Inconel 625-GRCop42 and GRCop42-Inconel 625 joints were fabricated using powder directed energy deposition techniques with different laser powers, and the defects, grain morphology, and phases were characterized. The results show that by increasing the laser power of the first layer, an Inconel 625 and GRCop42 joint without fusion defects can be fabricated. In this study, GRCop42-Inconel 625 connectors were prepared using a Meltio M450 LDED device. In the basement remelting at the junction of GRCop42 and Inconel 625, it was found that the composition of the melt pool induces liquid insolubility, resulting in the solidification of copper-deficient liquids to form an island structure that is prone to cracking. Due to the low volume fraction of intermetallic phase precipitation, the increase in laser power reduces the brittleness of these islands.
Figure 1. Pictures and schematics of the Meltio M450 printhead, powder nozzle and laser outlet locations.
Figure 2. (a) Schematic diagram of the sedimentation sequence studied. (b) Inconel 625 deposited on a GRCop42 substrate, and (c) GRCop42 deposited on an Inconel 625 substrate with EDM cuts on the substrate for microstructure characterization.
Figure 3.Etched light micrographs of GRCop42 deposited onto Inconel 625 substrate at (a) 200 W, (b) 400 W, (c) 600 W, and (d) 800 W. Dark areas are copper-rich, while gray areas are copper-deficient.
图4. (a) STEM-EDS 图和相应的SAD图样：(b)沿着[412]区轴的Cr-Ni-Mo P相；(c)沿着[112]区轴的Ni-Cu相，以及(d)沿着[101]区轴的Cr-Ni-Nb C14-Laves相。 (a)中的数字表示SAD收集区域。
图5. (a) Inconel 625粉末和(b) GRCop42粉末的SEM 显微照片。
In this study, the effects of laser power and deposition sequence on GRCop42-Inconel 625 joint defects and tissues were investigated.
When depositing Inconel 625 on GRCop42, insufficient fusion occurs due to the high thermal diffusivity of the GRCop42 substrate. This problem can be mitigated by increasing the laser power deposited in the first layer of Inconel 625. If the weight of the remelted GRCop42 substrate is less than 20%, liquid non-meltability can be avoided and crack-free bimetal joints can be created.
When GRCop42 is deposited on Inconel 625, remelting the Inconel 625 substrate creates a melt pool composition that results in a lack of liquid mixing between copper-rich and copper-deficient liquids. Solidification of copper-deficient liquids results in island-like structures with Cr-Ni-Nb C14-Laves (HCP) and Cr-Ni-Mo P (orthogonal) intermetallic phases, which are prone to cracking.
By increasing the laser power, the brittleness of the island structure in the GRCop42 and Inconel 625 joints can be reduced, allowing more Inconel 625 substrates to be remelted in the first layer. This will increase the volume fraction of the nickel-rich FCC phase and reduce the volume fraction of the brittle intermetallic phase in the island structure, thereby reducing the susceptibility to cracking.
Although the LOF and brittle phases were not present at the junction of Inconel-GRCop42, the brittle phase could not be completely eliminated at the junction between GRCop42 and Inconel 625 due to the presence of liquid mismiscibility in the liquid mixture of GRCop42 and Inconel 625. Therefore, future work should focus on the development of transition components for use between Inconel 625 and GRCop42 to avoid liquid separation (miscible gaps) and subsequent brittle phase formation.
Paper Links:
https://doi.org/10.1016/j.matdes.2024.112944
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Application of laser intelligent manufacturing in new energy vehicles:
July 29-31, 2024, Hefei Fengda International Hotel, Anhui
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