Combined use of blackbody and infrared radiation for accurate measurement of temperature field of aluminum alloys

Temperature is considered a critical factor in improving the quality of workpieces in the manufacturing of aluminum alloys. To improve the temperature measurement accuracy of aluminum alloys and realize on-line measurement, this paper proposes a method for measuring the temperature field of aluminum alloys with infrared radiation combined with blackbody spots calibration. Since the emissivity of aluminum alloys changes with the surface characteristics of an object, there is a certain difference between the directly measured temperature using the infrared thermal imager and the actual temperature of the aluminum alloy surface. For this purpose, a correction method of infrared radiation temperature field of aluminum alloy based on image mapping theory was established. The uniform and non-uniform temperature fields of the aluminum alloy workpiece were designed, and the temperature field of the aluminum alloy plate was reconstructed based on the image mapping theory and the blackbody spots temperature. The study reveals that accurate measurement of the temperature field of aluminum alloys can be achieved based on infrared radiation combined with blackbody spots online calibration, and the maximum error is 1.5 K. Therefore, the method is suitable for industrial applications of aluminum alloys where emissivity varies with temperature.