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Ultrasonic method applied to defects identification in the forging ingots

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The typical massive forging ingots produced in the steelwork has a mass of about 10÷100 T (Fig. 1). According to the technology of casting a porosity is expected along the ingot axis (Fig. 2). Each forging ingot is subjected to an ultrasonic test at a production line. But the result of this kind of industry test are not evident. In the case of the ingot of the mass about 12 T the acoustic signal indicated porous less than 1 mm longue (reduced distance). However, in the case of the ingot of the mass about 50 T the acoustic signal was completely damped by the grains boundaries so that no results of acoustic measurement were obtained. Therefore, some additional tests have been made by means of the light microscopy (LM) and scanning acoustic microscopy (SAM) for six samples along a given radius of the ingot shown in Figure 1. EXPERIMENTAL The results of the microstructure observation are shown in Fig. 3. A morphology of a one defect can be shown in more details (Fig. 4). The light microscopy is not able to reveal all the details of morphology of some single defects as these shown in Figures 3 and 4. Therefore, an attempt to identify the details of some defects was done by the scanning acoustic microscopy (Fig. 5, 6, 7a). Identification of the defects is performed by the SAM technique through density analysis of the different sample sublayers (Fig. 6). Microscope reveals a defect by comparison of the difference between density of bulk sample and density of a given defect. It is possible because scans can be made at different fixed distances. ˗ Fig. 1. Massive forging ingot produced in the steelwork Rys. 1. Masywny wlewek kuzienny produkcji hu[...]

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