Ultrasonic Evaluation of Porosity in Aluminum Cast Materials.

摘要

A new quantitative ultrasonic method was developed for gas porosity evaluation. The method, which is based on ultrasonic attenuation measurements and spectroscopic analysis of the ultrasonic reflected pulse, is capable of determining gas porosity in the range from 0.1% - 6% volume fraction and for pore sizes from 50 - 55 microns. The range is actually defined by the applied ultrasonic frequency which was from 1 - 20 MHz in this work, which can be extended (i.e. for smaller pores) by using high frequencies. This is the range encompassing all premium aluminum casting used in aerospace applications. This method can be used in plate-like geometries with thicknesses up to 3 - 4 inches. The technique can also be automated and controlled by a computer. Keywords: Cast aluminum gas porosity; Ultrasonic test; Structural materials; Porosity; Aluminum castings. (KT)