Microstructure Investigation, Hot Tensile and Hot Corrosion of IN۶۰۰ to Nimonic ۷۵ heterogeneous Connection in Spot Welding

Nimonic ۷۵ and Inconel ۶۰۰ alloys are the Nickel-based superalloys which are used in manufacturing gas turbine components. In the current research, a superalloy Ni-based Nimonic sheet and Inconel ۶۰۰ were used, joint by resistant spot welded (RSW) machine at currents of ۲, ۴, and ۶ kA, pressure of ۵ and ۷ bar, and times of ۰.۶, ۰.۹ and ۱.۲. Non- destructive inception methods and light and scanning electron method (SEM) and light optic microscope (LOM) were used to evaluate joints' quality. Shear and micro-hardness test was used to check the mechanical properties of the joint. The findings indicate that the most appropriate welding connection of inhomogeneous points at the current of ۴ kA was the holding time ۰.۹ second and electrode force ۷bar. The analysis of microstructure consisted of ۳ welding zones which are affected by heat and the base metal. The warm corrosion scanning microscope test results at ۶۰۰ °C and ۸۰۰ hours confirmed that the existence of a chromium oxide layer on the surface of the superalloy, which has the main role in protecting the piece in the output temperature.