Multiphysics Simulation Study on Impact of Inter-Layer Characteristics on Microwave Joining of Hastelloy C-276
摘要
Microwave processing of metallic joints is emerging as a new technique due to its faster processing and quality of joints produced. This study investigates the microwave-assisted joining of Hastelloy C-276 plates through a multi-physics simulation, employing three interlayer powders: Hastelloy C-276, EWAC, and Inconel-718. Simulations were performed at interlayer distances of 0.25, 0.5, 0.75, and 1 mm under microwave irradiation. Experimental validation was carried out using Hastelloy C-276 interlayer powder (~ 15 ± 5 µm) in a multimode microwave applicator operating at 900 W and 2.45 GHz. Simulation results revealed an increase in the electric field norm (4370 V/m to 4760 V/m) and resistive losses (28.6–37 MW/m3) with increasing interlayer distance, while thermal stresses exhibited decreasing trend (623–609 MPa). The predicted joint formation times were 750 s for Hastelloy C-276, 800 s for EWAC, and 770 s for Inconel-718, with the Hastelloy C-276 simulation results aligning well with experimental findings (750 ± 10). Microstructural Characterization of Hastelloy C-276 joints processed between 630 to 780 s revealed significant reduction in porosity (from 12 ± 0.7% to 0.015 ± 0.01%) and grain size (from 0.30 ± 0.06 µm to 0.15 ± 0.03 µm), indicating complete melting, and successful metallurgical joint formation.