Nickel based superalloy welding practices for industrial gas turbine applications
The continued drive for increased efficiency, performance and reduced costs for industrial gas turbine engines demands extended use of high strength-high temperature capability materials, such as nickel based superalloys. To satisfy the requirements of the component design and manufacturing engineers, these materials must be capable of being welded in a satisfactory manner. The present paper describes the characteristic defects found as a result of welding the more difficult, highly alloyed materials and reviews a number of welding processes used in the manufacture and repair of nickel alloy components. These include gas tungsten arc (GTA) and electron beam (EB) welding, laser powder deposition and friction welding. Many of the more dilute nickel based alloys are readily weldable using conventional GTA processes; however, high strength, precipitation hardened materials are prone to heat affected zone and strain age cracking defect formation. A number of factors are found to affect the propensity for defects: composition (aluminium and titanium content), grain size, pre- and post-weld heat treatment, as well as the welding process itself (control of heat input and traverse speed). Process parameter identification is still largely empirical and a fuller understanding of the joining processes is dependent upon the development and application of more sophisticated numerical modelling techniques.
Performance Deterioration in Industrial Gas Turbines
This paper describes the most important factors affecting the industrial gas turbine engine performance deterioration with service time and provides some approximate data on the prediction of the rate of deterioration. Recommendations are made on how to detect and monitor the performance deterioration. Preventative measures, which can be taken to avoid or retard the performance deterioration, are described in some detail.
gas turbine magnetic field positioning system magnetic resonance magnetic resonance imaging electromagnetic field communication terminal indoor positioning gas turbine engine positioning method magnetic flux field strength external magnetic field industrial gas turbine american national industrial ga oxygen saturation positive linear operator turbine component magnetic fluid magnetic field strength damage index high magnetic field presidential election pulse oximeter static magnetic field network failure indoor positioning method strong magnetic field voter model gas turbine component pulse oximetry sample variance voting protocol static magnetic solar cell array model dynamic alternating magnetic field magnetic resonance imaging. cardiac monitoring resonance imaging. laser communication terminal clinical magnetic resonance voter registration main magnetic field election campaign low magnetic field median voter gas turbine material american national election surface magnetic field national election national election study direct democracy voter turnout phantoms, imaging oxygen saturation test result