A Comparative Studyon Characteristics of Inconel-625 Joints Developed through Microwave Hybrid Heating and Tungsten Inert Gas Welding

Abstract

In recent years, microwave welding has received attention for joining of similar and dissimilar metals due to its major advantages like volumetric heating, selective heating of target materials, energy saving and sustainability. In the present work, the microstructural characteristics and mechanical properties of Inconel-625-welded joints developed through microwave hybrid heating and those produced by TIG welding have been compared. Welding through microwave hybrid heating (MHH) was carried out using Inconel-625 interface filler powder of 50 μm size, while TIG welding was carried out using ERNiCrMo-3 filler wire of 2.5 mm diameter which had a composition similar to that of Inconel-625 alloy. The welded samples were characterized in terms of microstructural observations and tensile and microhardness properties. The study reveals that the joining of bulk metals through MHH has potential in manufacturing industries in the near future. TIG-welded joints exhibit superior strength compared to MHH joints because of fine grain structure, lower amount of segregation in the weld zone and also smaller width of the weld zone in joints developed through MHH. The hardness in the weld zone of welded joints in both the cases is observed to be almost the same. Use of a finer interface filler of 20–25 μm particle size may further contribute to improving the mechanical properties of the joints developed through MHH. Furthermore, the use of industrial microwave furnace may improve the strength of MHH-welded joints as the process may be integrated with real-time temperature measurement of the joint zone so as to achieve better control over the process.