Research On The Characteristics Of Ultrasonic Signal Of The Organization Of TC4Titanium Alloy

In order to improve the forging process of TC4titanium alloy, the organization ofTC4titanium alloy after being forged needs to be known. Conventional method forthe analysis of the microstructure of materials is metallurgical method, metallurgicalmethod will cause material damage, parts waste, and time-consuming. This paperdoes research on TC4titanium rolled ring, using two parameters which can bemeasured for the ultrasonic evaluation of materials-ultrasonic velocity andattenuation of ultrasound to evaluate the ratio of primary α phase and the averagegrain size of the α phase of the TC4rolled rings organization.This paper first uses metallurgical method to obtain the phase diagram of thesample of TC4titanium rolled ring, and extracts the characteristic value oforganization based on ImageJ digital image processing software, including the ratio ofprimary α phase and the average size of the grain of α phase. Using the waterimmersion ultrasonic scanning system to obtain the ultrasound data of sample. Thevelocity of longitudinal wave of the sample is measured by ultrasonic pulse reflectionmethod, meanwhile the sound attenuation coefficient of the sample has beenmeasured, doing spectral analysis of the bottom echo, studying the variation of thecenter frequency of the bottom echo. The parameters of the organization of materialsin this paper are the area of primary α phase and the grain size of primary α phase,ultrasonic parameters are the velocity of sound, sound attenuation and frequency shiftof bottom echo, using the SPSS statistical analysis software to analyze thecharacteristic correlation between the parameters.The authors suggest to evaluate the trend of that the grain shape is close to theequiaxed according to the correlation between the area of primary α phase and thegrain size of primary α phase, and evaluate the magnitude and distribution of internalresidual stress according to the correlation between the ultrasonic velocity andparameters of the organization of the material, and evaluate the morphology of thesecondary α phase on β transformation matrix according to the correlation betweenthe ultrasonic attenuation and the parameters of the organization, and to evaluate thestate of the residual stress according to the correlation between the ultrasonic velocityand sound attenuation. The results have shown that: the organization of TC4titanium rolling ring is fuzzy grain structure, the primary α phase mainly distributes as thespherical, there is residual stress in the rolled ring of TC4titanium alloy, and themagnitude and uniformity of the residual stress is not the same with differentpositions, the grain boundary of the primary α phase is rough and will cause seriousscattering attenuation, which can be verified from the correlation between theattenuation coefficient and the organization, it can be known that the bigger the grainsize is, the more serious the scattering will be, and the frequency of the spectrum ofthe echo moves to a lower frequency with the increasing grain size by analyzing thespectrum of the bottom echo of the sample with different grain size.The research results in this paper are achieving the ultrasonic nondestructiveevaluation of the organization uniformity of TC4titanium alloy rolled ring, so that itcan guide the improvement of the rolling process of TC4titanium alloy with higherpractical value, it is expected to be extended to the evaluation of the distribution ofresidual stress in the ring.