Features of the process of hot extrusion of blanks of the rotor blades of a GTE compressor

Purpose. Improving the quality of manufacturing of blanks for compressor rotor blades by hot extrusion. Research methods and equipment. The research was carried out using a crank press with a force of 1000 kN, in split dies in accordance with a serial technological process. The dies were heated up to 150 ... 200 °С, to improve the work when extruding the blanks of the rotor blades made from the titanium alloy ВT8. The thickness of the copper coating was measured with an ИTMП-3 magnetic induction device with an error of ± 2 μm. X-ray spectral microanalysis was performed on an ISM-6360ALA scanning microscope. The billets were heated in an MП-2В furnace. Results. It has been established that the quality of blade blanks made of ВT8 titanium alloy obtained by hot extrusion is influenced by the state of the copper coating, which is preliminarily applied to the surface of the original blank. When the initial blanks are heated, copper is oxidized and in the temperature range of 250…700 °С the oxidation rate proceeds according to a linear pattern, and after 700…750 °С – according to a parabolic pattern. Oxidation of the copper coating occurs unevenly not only within one workpiece, but also within the batch, which leads to a decrease in durability and deterioration of the surface quality of the blade workpieces obtained by hot extrusion. Research carried out by X-ray spectral microanalysis of the copper coating revealed the presence of aluminum oxides of varying degrees of dispersion. The source of this material in the copper coating is caricature of corundum used in blowing into the surface of the billet, which is the reason for the appearance of scoring on the blade blank. It was also found that longitudinal marks on the blade are a consequence of the appearance of a matrix of tubercles (sagging) on the working surface of the die, caused by the adhesion of the deformable material of the blade to the base metal of the tool. Scientific novelty. The regularity of the influence of the heating temperature of the initial blank of the blade on the oxidation rate of the copper coating has been established. The mechanism of the influence of the oxidation of the copper coating and the adhesion of contacting materials during hot extrusion on the surface condition of the resulting blanks is disclosed. Practical value. The results obtained make it possible to improve the quality of the manufactured blanks of the compressor rotor blades by hot extrusion.