超声振动方向对激光定向能沉积Inconel 718性能影响研究OA北大核心CSTPCD

Inconel 718, a prominent nickel-based superalloy, finds widespread use in the aerospace industry due to its exceptional mechanical properties at elevated temperature. However, the pursuit of enhancing these properties further through LDED necessitates an understanding of the influence exerted by ultrasonic vibration on the process. To address this need, a comprehensive study was undertaken with the objective of elucidating the impact mechanism of ultrasonic vibration direction on the LDED of Inconel 718 components. The research aims to furnish a reference framework for ultrasound-assisted high-quality formation within the LDED domain. Methodologically, the study involved conducting experiments on LDED of Inconel 718 parts assisted by multidirectional ultrasonic vibration. The effects of ultrasonic vibration applied in distinct directions—namely, the building direction, overlapping direction, and scanning direction—on the molten pool's flow behavior, microstructural development, and mechanical properties were meticulously investigated. This was achieved through the synergistic integration of in-situ molten pool monitoring technology. The experimental outcomes were revealed. It was observed that the application of ultrasonic vibration in varied directions significantly perturbed the dynamic flow within the molten pool. Notably, the introduction of overlapping directional ultrasonic vibration resulted in an impressive 86.4％ augmentation in the wetting area of the molten pool, which also transitioned to a more geometrically regular shape, effectively mitigating the trailing effect typically associated with the process. Furthermore, the scanning direction vibration proved to be the most efficacious in terms of microstructure refinement, achieving a notable reduction of 46.9％ in crystal size. The transformation to equiaxed crystals was found to be superior in the horizontal plane compared with the building direction. Concurrently, the Laves phase particles experienced significant spheroidization and a reduction in size under the influence of building direction vibration. Microhardness testing corroborated these findings, indicating a substantial increase from the control group's 210.4HV0.2 to 232.5HV0.2, 230.9HV0.2, and 233.9HV0.2 in the building, overlapping directional, and scanning directions, respectively. The trends in microhardness were congruent with the changes in crystal size, signifying a direct correlation between the two parameters. Additionally, the study illuminated the nuanced influence of ultrasonic vibration in the horizontal plane. The scanning direction, in particular, not only enhanced the material's strength but also preserved its ductility to a commendable extent. The overlapping direction of ultrasonic vibration demonstrated an adept ability to eliminate anisotropy, culminating in a remarkable balance of hardness, strength, and plasticity. In conclusion, the study underscored the utility of ultrasonic vibration in different directions to modulate the dynamic fluidity of the molten pool through distinct inertial forces and thermal flow alterations. The tangential application of ultrasonic vibration emerged as having an exceptional comprehensive capability in enlarging the wetting area of the molten pool and refining its dynamic shape. The directional propagation attenuation of ultrasonic intensity and the concomitant acoustic pressure gradients played pivotal roles in the pronounced crystal refinement and Laves phase spheroidization observed in the scanning and building directions, respectively. These transformations led to correlated enhancements in microhardness and tensile properties. Ultrasonic vibration also served to equalize the mechanical properties, bolstering tensile strength, yield strength, and ductility of the material, with a particularly pronounced ability to eliminate anisotropy in the overlapping direction. Depending on the specific requirements at hand, applications could selectively employ the appropriate directional ultrasonic vibration or a strategic combination thereof to achieve an optimal match of molten pool fluidity, microstructural morphology, and mechanical properties in Inconel 718 components. The insights gleaned from this study are not only instrumental in advancing the state-of-the-art in LDED but also hold significant implications for a broader field of materials science and manufacturing technology. By harnessing the power of ultrasonic vibration, researchers and engineers can now more precisely manipulate the microscopic attributes of materials, thereby opening up new avenues for innovation and optimization in industries ranging from aerospace to automotive and beyond.