Fatigue testing of Inconel-625 coatings on carbon and stainless steel after one and three weeks of exposure to aqueous electrolytic solution

Purpose - This paper seeks to examine the fatigue properties of HVOF sprayed Inconel-625 coating of steel substrate before and after the aqueous corrosion. Design/methodology/approach - Workpieces were cut from steel sheets. After chemical and ultrasonic cleaning, workpiece surfaces were sand-blasted and HVOF sprayed Inconel-625 coated. The coated and un-coated surfaces were subjected to the aqueous corrosion tests for one and three weeks. After the completion of the corrosion tests, fatigue properties of the workpieces were examined. Findings - Stainless steel coated workpieces demonstrated excellent fatigue life resistance versus coated carbon steel workpieces. Stainless steel workpieces apparently have a high-cycle fatigue represented by in excess of 1.50 million cycles without cracking, thereby assuring a high-fatigue life. The carbon steel specimens have low-cycle fatigue and consequently a short fatigue life. In addition, high velocity impacting of splats on to the workpiece enhances the hardness of the surface. This, in turn, improves fatigue properties at the interface, particularly for stainless steel workpieces. Research limitations/implications - The tests can be extended to include the duplex treated workpieces such as the laser treatment of surface after HVOF sprayed coating. This enhances the bonding of the coating through thermal integration of the coating and the base substrate material. Practical implications - The results can be used to assess the HVOF sprayed coatings. Originality/value - This paper provides information on the fatigue behavior of HVOF sprayed coatings when subjected to the cyclic load and offers practical help for the researchers and scientists working in the coatings area.