High Temperature Mechanical Constants of TC4 alloy Detected by Laser Ultrasonic

Abstract

Mechanical constants are the fundamental parameters for characterizing the mechanical properties of materials. Laser ultrasonic is a new non-destructive testing method characterized by long-range and non-contact. It is particularly suitable for detecting the mechanical properties of materials in harsh environments. TC4 alloy is one of the most important alloys for the production of engine blades, which is working at a high temperature of about 300–500℃. In this paper, the mechanical constants (elastic modulus and Poisson's ratio) of TC4 alloy at high temperatures are studied based on the finite element method. The mechanical constants are determined by their relation to the velocity of the ultrasonic wave. The finite element model of the laser-induced multi-mode wave at room temperature is established. Compare with the experimental results, the Rayleigh wave velocity error is 1.70%, and the longitudinal wave velocity error is 1.18%. The numerical results agree well with the experimental results, which confirms the correctness of the model. On this basis, further inversion of elastic modulus and Poisson's ratio of TC4 alloy at high temperature. It is found that elastic modulus and Poisson's ratio of TC4 alloy have a quadratic relationship with temperature. The mechanical constants at high temperatures are predicted, and the relative error is less than 4%. In this paper, the numerical results are in good agreement with the theoretical values, which verifies the validity and reliability of the model. It provides a reference for the further use of laser ultrasonic to determine the mechanical properties of materials at high temperatures.