Thermal behavior analysis of UHSS rectangular plates via gradient thermoforming process under coupled heat conduction and radiation

The mechanical properties of ultrahigh-strength steel (UHSS) fabricated by the gradient thermoforming process (GTP) are directly governed by conduction-radiation coupled thermal behaviors. However, the thermal behavior of UHSS during gradient thermoforming remains unclear. This study examined the specific effects of coupled thermal conduction, radiation, and convection on heat transfer in UHSS via GTP. An effective thermal model was proposed by considering heat transfer mechanisms, including coupled heat conduction and radiation. An analytical model for predicting the 3D transient temperature within rectangular UHSS plates during GTP was developed with the separated variable method. The model incorporated thermal conduction-radiation coupling and was validated through comparisons with existing references. Furthermore, the effects of different physical parameters on the temperature distribution of the UHSS rectangular plates in the GTP were explored. The results demonstrate that the heating rate, geometry, and model parameters significantly affect the temperature distribution of GTP-built UHSS rectangular plates. This research provides a theoretical foundation for optimizing the process parameters and material design and improving the formation quality of GTP-built UHSS rectangular plates.