Ultrasonic testing

Ultrasonic non-destructive testing is particularly common and is characterised by its capacity to provide reliable indications on the presence of defects or inclusions in an alloy. Ultrasonic radiation is in fact easily propagated in metal materials. It is, however, reflected, attenuated or deflected if it encounters a cavity or inclusion. With different types of probes, it is, therefore, possible to detect the presence of other more frequent classes of flaws in a foundry casting, such as shrinkage cavities, gases trapped or developed by the interaction between sand, binders and cast iron, slag inclusions and oxide particles. Depending on the type of instrumentation used, the precision of the localisation of the defect may vary.

Ultrasonic testing

X-ray testing

It is well known that X-rays, depending on their intensity, can pass through a metal, in a manner which also depends on the intrinsic characteristics of the material. The X-ray resulting from this makes it possible to detect the presence of cavities (solidification shrinkage, trapped air and gases) within a casting. Conventional x-ray testing provides typically two-dimensional information, with a level of resolution in the millimetre range. In a ferrous material such as cast iron, the attenuation of radiation by the material itself is rather significant, and this determines a limit in the thickness of the analysable parts.

Using Industrial Computed Tomography, it is also possible to carry out a highly detailed three-dimensional reconstruction of the cavity in the material, which can be integrated, for example, with CAD-CAM systems. However, the time required to analyse a part can be relatively long.

X-ray inspection

Other types of check

There are also other types of non-destructive testing applicable to the cast iron foundry field. To this end, please note:

Liquid penetrant tests
Eddy-current testing
Magnetic particle testing

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