Emissivity Calibration and Temperature Measurement of High Strength Steel Sheet in Hot Stamping Process

Abstract

In order to meet the requirements of improving hot stamping process, the temperature distribution of high strength steel (HSS) sheets should be observed. However, the accurate measurement of temperature field in transfer where the temperature falls rapidly proves to be difficult due to the limitation of thermocouple. The infrared thermography could be used for accurate measurement of temperature field but the emissivity which is crucial to the accuracy and reliability of measurement results is not available. In this paper, a method to calibrate emissivity of HSS blank was developed for temperature measurement in hot stamping using infrared thermography. Experiments were performed on the emissivity calibration of the HSS Advanced 1500 in hot stamping. Emissivity dependence on temperature was investigated, so was the impact of little variation in emissivity on the temperature measurement. The validation tests were made and the results reveal that this calibration method of emissivity is accurate and feasible. This method is also appropriate for the calibration of emissivity in other temperature measurement situations.