Metallurgical Characterization of a Low Carbon Steel Microstructure Using Linear and Nonlinear Ultrasonics

摘要

In this study, linear and nonlinear ultrasonic (UT) methods are utilized to evaluate the microstructures of A572 low carbon steel samples that were intercritically heat-treated at three temperatures and quenched to room temperature. The microstructures were also qualitatively and quantitatively assessed using standard metallography. ImageJ software was used to measure the amount of the phases. Correlations between ferrite content and linear velocity and the acoustoelastic coefficient are established. The experiments show that the UT linear and nonlinear velocities are affected by varying the amounts of ferrite and martensite. The acoustoelastic coefficient is found to be more sensitive to small changes in ferrite volume fraction.