Effect of ternary atmosphere on the organization and properties of Inconel 690 GTAW welded joints

Abstract This study employs the Ar-He-H 2 ternary shielding atmosphere to enhance the weld quality and efficacy of Inconel 690 alloy gas tungsten arc welding (GTAW). The methodical examination of its impact on the law’s mechanical properties, elemental distribution, and weld microstructure. The results indicate that the ternary atmosphere weld has a lower proportion of planar dendritic crystals than the conventional Ar-He binary atmosphere. Additionally, the grain size increases and Cr 23 C 6 carbides are significantly enriched at grain boundaries. The EBSD analysis indicates that the proportion of small-angle grain boundaries (2°∼5°) decreases, while the proportion of large-angle grain boundaries increases, and the grain orientation is more concentrated. According to mechanical property tests, the tensile strength, elongation, and yield strength of the joint decreased as the He content increased. However, the weld’s hardness marginally increased as a result of the carbide-strengthening effect. The ternary ratio of 80% Ar+15% He+5% H 2 is recommended considering the arc penetration and mechanical properties. The generation of gas gaps is mitigated by increasing the shielding gas flow. The results establish a theoretical foundation for the implementation of ternary atmosphere engineering and the optimization of the GTAW process for Inconel 690 alloy.