Increasing fatigue life of gte compressor disks made of titanium alloys by discs treatment in fluidized abrasive layer

Abstract

Purpose. Increasing fatigue life of GTE compressor disks made of titanium alloys by discs treatment in the fluidized abrasive bed.Investigation methods and equipment. The investigations were carried out using LPC stage I discs of ВТ3-1 alloy and HPC stages IV and V discs made of ВТ-9 titanium alloy of Д-36 aircraft engine.In the process of discs manufacture the following manufacturing methods were used: ultrasonic hardening and treatment in the fluidized abrasive bed.The ultrasonic hardening was carried out using Motor Sich serial installation and the fluidized abrasive bed treatment – using the АПС-600А installation.The discs were tested before and after the treatment on a special electrohydraulic test bench with a multi-axis loading system using a fixture reproducing radial and circumferential stresses at the base of an inter-slot projection.The testing was carried out at specimens temperature of 390 °С and 430 °С.For measuring the length of cracks and the time of their occurrence in the slots, the discs were inspected by ЛЮМ-1-ОВ method ant using the МПБ-2 microscope and КМ-8 cathetometer.Obtained results. It has been established that for LPC stage I discs made of ВТ3-1 alloy the increased fillet radius combined with subsequent treatment in the fluidized abrasive bed increases fatigue life of the discs by 6 times before crack occurrence, and increases durability of the disc with a crack by 5.5 times.Durability of a disc is within 41 % to 77.8 % of their total fatigue life .Treatment of the compressor dics made of ВТ-9 titanium alloy in the fluidized abrasive bed creates residual compression strain up to 300 MPa in the surface layer.Testing of the LPC stage 1 discs showed that frequency and shape of the discs effect both fatigue life prior to a crack occurrence and durability prior to discs destruction within the entire investigated loading frequency range of 0.01 Hz to 1.0 Hz.Testing of HPC stages IV and V discs of ВТ-9 titanium alloy showed that temperature variation within 390 °С to 430 °С did not contribute significantly to the fatigue life change. Introduction of endurance into the loading cycle has a considerable effect on the low-endurance fatigue of the compressor discs.Increase of the soak time up to 60 seconds under the same loading conditions decreased fatigue life of the full-scale specimens by 10 times.Scientific novelty. It was demonstrated that treatment of the compressor disks made of titanium alloys in the fluidized abrasive bed increases their cyclic life by 5 to 6 times in comparison with their treatment in accordance with serial technology.Practical effect. A process sheet was proposed and the modes of compressor discs treatment in the fluidized abrasive layer were developed that provide increase of the fatigue life by 5 to 6 times as compared with a serial technology.