Effect Of Activating Flux On The Properties Of Ni-based Inconel 601 Alloy Joints

Inconel alloy 601 is a typical Nickel-baed alloy. An outstanding characteristic of Inconel alloy 601 is tie resistance to high-temperature oxidation. Of particular significance is its resistance to oxidation at temperatures up to 1200℃. The properties of Inconel 601 make it a general-purpose engineering material for applications that require resistance to heat and corrosion, such as gas turbine aeroengine, high temperature air furnace, engine blade, and combustion tube and so on.Inconel alloy 601 exhibits good weldability. However, due to its large surface tension, the fluidity of the welding pool is poor and it is difficult to get a larger weld penetration. The weld penetration of Inconel alloy 601 is less than the half of carbon steel under the same welding parameter. In order to improve the fluidity of the welding pool, activating flux was applied on the surface of plate. The weld penetration is greatly improved compared with the conventional TIG welding and thus enhance the process efficiency.To evaluate the effects of welding parameters-welding current, welding speed, arc length-on the weld penetration, weld width, depth-to-width ratio, this paper introduced the conception of Response Surface Method (RSM) to optimize the welding parameters. The fitting formulas of each response were obtained by analyzing the sequential model sum of squares and the lacking of fit testes. The optimal parameters (115A, 171mm/min and 1mm) were obtained by the analyzing of Design Expert software. Due to the specialty of welding pool,'Weld Pool Oscillation Method'was applied to measure the surface tension of welding pool with and without activating fluxes. The mechanical properties of the joints were also tested to study the influence of the activating fluxes.The result shows that the optimal parameters of the welding were accurately and quickly obtained by the RSM method. Contract to the conventional TIG welding, the surface tension of the A-TIG welding pool is greatly reduced and a deeper penetration was obtained due to the application of the activating fluxes. Though adding activating fluxes and the bending property changed insignificant. However, the distribution of the micro-hardness of A-TIG increased. Moreover, the fracture modes of the joints changed significantly. Due to the reduced size of weld bead and HAZ, it changed from brittle fracture to ductile fracture since the application of activating fluxes.The study found out that the application of the activating fluxes could significantly reduce the surface tension and improve the weld penetration. Furthermore, the bending property and distribution of the micro-hardness did not change with the use of activating fluxes. However, activating fluxes can significantly improve the tensile property of the joints. The results meet the requirement of the production.