INFLUENCE OF HEAT TREATMENT ON THE STRUCTURE OF A BLANK MADE OF HEAT-RESISTANT NICKEL ALLOY EP741NP FROM METAL POWDER OBTAINED BY GAS ATOMIZATION

The prospects of using granule metallurgy technology for manufacturing gas turbine engine (GTE) disk blanks are considered. It is shown that there are two main methods for obtaining powder for manufacturing gas turbine engine parts – gas atomization and centrifugal spraying of cast high-speed rotating blanks. The main advantages and disadvantages of the above methods of obtaining metal powders are considered. Metal powder was obtained from heat-resistant nickel alloy EP741NP by gas atomization. The mode of hot isostatic pressing of the compacted blank was carried out. The chemical composition of the EP741NP alloy blank after hot isostatic pressing (HIP) was studied. Samples were cut to assess the effect of heat treatment on the structure of the studied blank. Factors influencing the selection of heat treatment modes for samples were analyzed. The heat treatment modes were selected to assess the influence of temperature-time parameters on the structure of the studied samples of the obtained HIP workpiece. The results of the microstructure analysis after HIP and heat treatment (HT) of the workpiece made of heat-resistant nickel alloy EP741NP from metal powder obtained by gas atomization are presented. The changes in the composition and quantity of carbide phases during heating are analyzed. The processes occurring during the decomposition of a supersaturated solid solution, coagulation of primary and secondary phases, dissolution of primary and secondary phases, and melting are considered. The temperature and time parameters at which the greatest change in the amount of carbide phases occurs are recorded. The results of digital analysis of the distribution of the intermetallic phase after hot isostatic pressing and heat treatment at the periphery and in the center of the samples are presented. The results of the influence of heat treatment on the formation of intermetallic phases are presented, and the influence of the selected heat treatment modes on the structure and grain grade of the studied samples is considered. Microstructural analysis of samples after hot isostatic pressing and various heat treatment modes was performed using optical and scanning electron microscopy. An optimal heat treatment mode was selected that promotes an increase in the volume fraction and average diameter of intermetallic phase components of the EP741NP alloy structure.