Coating of Inconel 718 Super Alloy with Stellite6 Cobalt-base Alloy Coated Layer via Tig Welding Process & Investigating the its Erosion Resistance & Hardness Behavior

Abstract

Heat treatable nickel-based super alloys have appropriate wear resistance to sweet and sour wear environments. Therefore, they are used in disparate industries such as petroleum, gas, and transportation. These super alloys have appropriate hardness, however, sometimes in the oil, gas, and military of this super alloy, more hardness is required to increase erosion resistance. Hence, it is efficient to apply cladding on the super alloy by cobalt-based super alloys.Surface cladding is one of the appropriate methods for increasing the service life of this class of cobalt-based super alloys is used. In the present research, Incoloy 718 were coated with stellite6 cobalt-based super alloys through GTAW method and examined the effect of TIG welding process parameters were examined on hardness and erosion resistance by conducting investigations such as Metallography, microhardness testing, SEM microscope analysis and erosion experiments.The results demonstrated that hardness and erosion resistance of the weld metal from surface to the depth of weld toes increased gradually. The gradual decrease of hardness of weld metal is pertinent to the reduction of the size and quantity of NbC and cobalt. Besides, by increasing the welding current (heat input) preheating temperature, the hardness and resistance to erosion in weld metal was decreased and increased, respectively. Upon increasing the intensity of the welding current and the number of coating layers the dilution value of the base metal in weld metal increases and decreased, receptively. By increasing of preheat temperature, the input value of the basic metal element decreased in coating layer.Finally, the highest erosion resistance is pertinent to the coated samples in 1. triple layer coating, 2. coated sample in the lowest welding current, 3. coated sample in the at 200 and 300 degrees centigrade preheating temperature.