Surface Residual Stress Measurement of Metal Material Using Ultrasonic

Abstract

To measure the surface residual stress using non-destructive testing method for the metal parts during manufacturing process is still a difficult problem. A plane stress state measurement method using ultrasonic is proposed. The characterization factor of grain orientation is introduced based on linear elasticity theory. And the influence mechanism of grain orientation on ultrasonic propagation is revealed. Considering the joint effect of material mechanical properties (elastic constants, grain orientation, etc.) and stress state on acoustic velocity, a plane stress component-acoustic velocity decoupling model is established. The effect of temperature and coupling state on ultrasonic attenuation, distortion and time-of-flight is analyzed based on longitudinal critically refracted (LCR) wave surface stress measurement principle, and a "one-transmitter-two-receiver" direct coupling wave-generation probe is designed. The variable cross-section aluminum alloy plate under uniaxial tension and the rolled aluminum alloy plate after friction stir welding are taken as typical objects. The surface stress measurement experiment is carried out by using the self-developed ultrasonic stress measurement system. The results of stress measurement are in good agreement compared with finite element method and hole drilling method, which provides a feasible solution for surface stress measurement of metal materials at the manufacturing site.