Effect Of Ultrasonic Loading Frequency On Fatigue Properties Of High Strength Steel FV520B-I

As a major advanced equipment used in many national economic fields,Centrifugal compressors have continuously increased their requirements for design and manufacturing with the continuous development of engineering technology.In practical engineering,fatigue failure of the impeller,the core component of the Centrifugal compressor,often occurs due to various cyclic loading.Therefore,the service life requirement of the impeller has reached 10~9 cycles,and it is of great significance to carry out research on the ultra-high cycle fatigue performance of high-strength steel FV520B-I,which now often uses ultrasonic fatigue experimental system due to the limitation of traditional fatigue experimental conditions.However,many researchers have found that the ultrasonic loading frequency will affect the experimental results for some metal materials,especially the material fatigue behavior and fatigue properties,and the study on the effect of ultrasonic loading frequency on fatigue properties of FV520B-I has not been carried out,which is of great practical significance.In this paper,the fatigue experiments at 140Hz and 20kHz are carried out for FV520B-I.The S-N curve of FV520B-I at 140Hz and 20kHz loading frequency was obtained by applying lognormal distribution function and three-parameter power function fitting according to experimental data.The comparison analysis shows that the fatigue life and conditional fatigue strength of FV520B-I at the ultrasonic loading frequency are greater than those at the traditional loading frequency.Then based on the effect of ultrasonic loading frequency on the fatigue properties of metal materials,an application method for the fatigue data conversion of alloy materials at the ultrasonic loading frequency is proposed,which can be used to transform fatigue experimental data at ultrasonic loading frequency into experimental data suitable for fatigue design and analysis.Finally,the conversion models of conditional fatigue strength and fatigue life for FV520B-I are established respectively,and the applicability o the model was verified.