Quantitative Uniformity Evaluation of Steel Slab Heating Temperature by Non-contact Measuring Approach

The aim of this work was to determine quantitatively the temperature uniformity of steel slab in high-temperature heating process under non-contact measuring conditions. Specifically, the temperature distribution of steel slab in heating process was obtained by infrared thermal imager, steel slab analog, and industrial image acquisition. The image isoline method was utilized to extract the non-uniform temperature region and temperature gradient of the steel slab. The local discrepancy function was used to measure the temperature uniformity of steel slab surface. Results showed that the problem of internal thermal conductivity of the steel slabs was reflected on the surface. The temperature of the cross section raised more slowly than that of the surface, but the temperature distribution was more uniform. More attention should be paid to the temperature distribution of the smaller surface and cross section rather than larger ones. The temperature uniformity degree of the surface of the steel slab samples from open literature was quantified respectively by 0.95, 0.92, 0.91, and 0.98. The steel slab with better quality would be obtained since the non-uniform heating could be adjusted according to the understanding of the distribution characteristics of the temperature field of the steel slab. This work was probably of great significance to increase the qualified steel slab, reduce scrap rate, and improve economic efficiency.