Weldability of haynes 188 cobalt based superalloy and AISI 316L austenitic stainless steel

Because of their high temperature and oxidation resistance, similar and dissimilar metal welding is needed in producing gas turbine and rocket engine parts, in which cobalt-based superalloys are also used. The fusion welding methods such as gas tungsten arc welding (TIG), Laser welding (LW), Electron beam welding (EBW), and Plasma arc welding (PAW) are widely used for dissimilar metals welding applications. Weld discontinuity such as solidification cracks and liquefaction cracks can occur in the weldment. One way to overcome these problems is to use a low heat input in the welding process. Force TIG welding machine, which has been developed in recent years, allows automatic welding with its integrated systems. Thus, it provides the opportunity to obtain the heat input homogeneously and to perform autogenous welding with its control of the welding parameters. The study aims to investigate the weldability of the Haynes 188 - AISI 316L couple, as supplied, automatically with the Force TIG welding machine, without opening the weld groove, and without using any filler metal (autogenously). For this purpose, the strength and hardness of the dissimilar welded sample were determined, and its microstructure was evaluated in detail.