Ultrasonic in-situ monitoring of solidification and melting behaviors of an aluminum alloy

Abstract

This paper presents a newly developed high temperature ultrasonic sensor and its application to in-situ observation of aluminum alloy during solidification and melting in temperature up to 800 ºC. The ultrasonic sensor mainly consists of a conventional piezoelectric transducer and a titanium buffer rod as an acoustic waveguide. The length is 300 mm. This sensor, owing to the unique characteristics of titanium, is highly expected to provide not only high acoustic coupling to molten aluminum but also high corrosion resistance. It is demonstrated that the titanium buffer rod has superior sustainability and wettability to the molten aluminum alloy. Using the ultrasonic sensor, the changes of the longitudinal velocity of the aluminum alloy during solidification and melting have been monitored as a function of temperature. Furthermore, a clear reflected echo from the solid-liquid interface of the aluminum alloy has been observed. The movement of the reflected echo due to the growth of the solid-liquid interface has also been monitored during cooling process. Thus, it is demonstrated that the developed ultrasonic sensor using a titanium rod is a promising tool for molten aluminum monitoring.

Numerical Investigation of Influence of Temperature on Propagation of Ultrasonic Waves in Waveguides with Mode Conversion

“…In order to find necessary deflection angle of the waveguide front surface, the material properties of the waveguide have to be known. For waveguides, used as thermal buffers, different materials are used: aluminium [3], [9], stainless steel [4], titanium [5], [8]. In our work ASTM Grade 4 Titanium was chosen.…”

Experimental investigations into the propagation of acoustic emission signals from particle impacts along a waveguide

“…Waveguides are widely utilised for acoustic emission (AE) detection in various industries, such as petrochemical engineering, gas transportation, metal casting and power generation [1][2][3][4]. In these cases, it is impossible to place an AE sensor directly on the surface of the examined specimen due to the inaccessible location on structure or the harsh industrial environment [5].…”