Effect of oxide scale on temperature-dependent interfacial heat transfer in hot stamping process

• We analyze the heat transfer phenomenon between oxidized blank and dies.
• We study the relationship between oxide scale thickness and heating time.
• We develop an optimization procedure to calculate the interfacial heat transfer coefficient (IHTC).
• The IHTC is affected by oxide scale thickness, pressure, and average temperature.

An optimization-based numerical procedure was developed to determine the temperature-dependent interfacial heat transfer coefficient (IHTC). The effects of temperature, pressure and oxide scale thickness were analyzed, for oxide thickness between 9 μm and 156 μm and pressure from 8 MPa to 42 MPa. Oxide scales and contact pressure both show distinctive effects on IHTC in the cooling process. The average IHTC decreases about 2461 W/(m2 °C) with the increase of oxide scale thickness and increases 2620 W/(m2 °C) with the increase of pressure. Based on the two-way ANOVA, the effect of contact pressure influences the IHTC most. Their mutual interaction is negligible. The IHTC decreases when the average temperature between the blank and die surface is above 250 °C and increases when the latent heat release.