Enhancing Radiative Heating of AlSi‐Coated Hot Forming Steel via Controlled Alkaline Surface Treatment

Aluminum–silicon (AlSi) coatings on steel substrates provide corrosion and scaling protection in hot forming, but their high reflectivity limits efficient radiative heat transfer during furnace heating. Although diffusion annealing, anodizing, or additional absorption coatings have been proposed to increase absorptivity, a simple alkaline surface treatment has not been explored in this context. This study investigates the effect of controlled alkaline pickling on AlSi‐coated 22MnB5 blanks. Microstructural, optical, and thermal properties are systematically analyzed. Selective dissolution of Al‐rich phases exposes Si‐rich structures, raising the absorption coefficient at a reference temperature of 950°C from 0.23 (untreated) to 0.50. Heating rates increase accordingly from 6.0 to 11.3 K s –1 , representing an improvement of up to 88%. Absorption coefficients and heating rates exhibit a strong linear correlation. An optimal process window (1.8–5.0 g m –2 specific mass loss) yields 40%–50% faster heating rates to reach 900°C. Overall, the results demonstrate that rapid alkaline surface modification provides a straightforward approach to significantly enhance furnace efficiency in hot forming. It also offers a promising pathway for energy reduction in automotive manufacturing.