Propagation characteristics of ultrasonic in SLM manufactured AlSi10Mg

Porosity is a crucial quality evaluation criterion in metal additive manufacturing. To investigate the propagation characteristics of ultrasonic longitudinal waves with different incident frequencies in AlSi10Mg prepared by selective laser melting, specimens with varying porosity were created using printing process adjustments. Ultrasonic longitudinal wave tests and COMSOL simulations based on 2.5 MHz, 3.5 MHz, 5 MHz, and 7.5 MHz incident frequencies were carried out to establish a linear relationship between average wave velocity, average attenuation coefficient, and porosity at different frequencies. Results indicate that sound velocity and porosity are inversely proportional for each frequency longitudinal wave, while the attenuation coefficient is proportional to the porosity. Linear fitting expressions suggest that the best fit for both sound velocity and attenuation coefficient occurs at 5 MHz. Simulation results demonstrate that using 5 MHz as the incident frequency can better balance detection sensitivity and linearity. These findings provide more data support for establishing the intrinsic connection between acoustic parameters and porosity of AlSi10Mg prepared by selective laser melting in the selected area and serve as a reference for selecting ultrasonic incident frequencies in practical inspection.