Temperature control by digital thermographic camera of aluminum sheets under high-dense electric pulsing

One of the main factors hindering the application of high-dense electropulsing technology is the lack of commercial devices to record the temperature of wrought semi-products and billets under conditions of ultrahigh heating rate and ultrashort annealing time. The paper presents the data on the control of temperature and duration of the stages of heating and cooling of rectangular plates with a thickness of 1 mm and gauge length of up to 92 mm out of cold- and cryo-rolled sheets of the 1560 (Al – 6Mg – 0.6Mn) and 1965 (Al – 8Zn – 2Mg – 2Cu – 0.1Zr – 0.2Sc – 0.1Mn) alloys during a single exposure to millisecond pulses with a current density of up to 90 kA/mm². The temperature changes were recorded using digital thermographic camera THT-600 with a frame rate of 50 Hz. It was found that the temperature measured in the central sample volumes coincides well with the calculated one under heating up to 200°C and weakly depends on their length. The temperature distributions over the width and length of the plates are heterogeneous, and the temperature gradient decreases with their length. The detection of volumes with an increased temperature along the longitudinal edges of the samples was originated by the elecropulsing skin-effect, and those with a reduced temperature near the boundaries of the treated zone were due to intense heat outflow through capture-current traps. The results can be used to improve methods of on-line temperature control of aluminum semiproducts under electropulsing treatment.

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