Application of ultrasonic non-destructive characterisation on materials' quality evaluation

In this present work, the non-destructive characterisation technique has been undertaken for evaluating the inhomogeneous nature of 6XXX aluminium alloy. Samples containing extrusion welds and metal inert gas joints were inspected by an ultrasonic immersion C-scan system. The inhomogeneous nature of materials was characterised by ultrasonic attenuation map. The relationship between attenuation and microstructural evolution, particularly in grain size distribution, was studied experimentally. Metallographic analysis shows that the grain size variation in each sample is in good agreement with the corresponding ultrasonic attenuation map. Moreover mechanical properties can be predicted qualitatively by the ultrasonic attenuation map. Experimental results demonstrated that, besides metallographic analysis and mechanical testing, the non-destructive characterisation technique can be an efficient method for quality control in the extrusion industry.