نوع مقاله : مقاله پژوهشی
1 گروه مهندسی مکانیک، دانشکده فنی، دانشگاه هرمزگان
2 گروه مکانیک، دانشکده فنی، دانشگاه هرمزگان
عنوان مقاله [English]
Currently, improving microstructure of new casted turbine blades by applying uniform pressure at high temperatures is considered as one of the common steps in their production. The operation performed on the serviced-exposed blades can be effective in extending the blade lifetime through the closing and welding of creeping cavities and micro cracks. Due to the lack of adequate existing information, the present study attempts to create the same conditions by studying the experimental process. For this purpose,at first, a special measuring fixture was designed and fabricated. Then, a disc containing 75 first-row blades of the Ruston power turbine was measured on longitudinal direction, and six of them were selected with the highest longitudinal creep. In the next step, the pressure and high temperature tank as well as the furnace needed for the tests were prepared and adjusted. The samples were then subjected to a pressure of 150 bar and a temperature of 380 ° C for eight hours. Metallographic studies showed that the percentage of γ^' phase in various areas of airfoil increased by about 25%, and the hardness in these areas was increased by a maximum of 7%, which, according to the operating conditions, indicated that the mechanisms for improving the microstructure were active. Using the experimental data and the Monkman-Grant relationships and the Larson-Miller parameter, it is expected that the creep life of this blades will increase by about eight thousand hours.