Mechanical and electrochemical properties of inconel alloy 617 after refurbishment through heat treatment

The transition piece in gas turbine is an important component, which joins the combustion chamber to the turbine nozzles. These pieces are made from an alloy that resist high temperature and thermal loading and being considerably expensive. The high operating temperature and thermal fatigue limit the lifetime of such component Consequently, the life extension of the alloy through sound refurbishment process is in demand. The refurbishment of Inconel 617 alloy after 37000 hours of operation in the field is considered through heat treatment process. Tensile and fatigue properties, as well as microstructures and elemental composition of the alloy before and after the heat treatment process are investigated. In addition, the electrochemical response of the heat-treated alloy is investigated through potentiodynamic surface testing. The heat treatment process is carried out at 1175 °C for one and two hours in air free furnace. It is found that the heat treatment of the alloy for one hour partially improves the cavitations at grain boundaries and the fatigue response of the workpiece partially improves. Further, dimples at grain boundary facets was noticed after the heat treatment which is an evident of ductility of the workpieces. Moreover, the corrosion resistance improves considerably for the workpieces subjected to one-hour heat treatment Consequently heat treatment of the Inconel 617 alloy after long term of operation improves slightly its properties and partial regaining of the alloy properties thought heat treatment with temperature rang and the duration employed in the present work is visible