Experimental-Numerical Approach to Determine the Heat Transfer Coefficients for Compound Forging Processes

Abstract:

For the reliable numerical simulation and design of compound forging processes involving dissimilar materials, an accurate representation of thermal boundary conditions is essential. In particular, the heat transfer coefficient (HTC) at the interface of the workpiece and the die strongly influences temperature distribution, material flow, and interfacial integrity. Despite its significance, the HTC is frequently modelled as constant in finite element (FE) simulation due to the lack of experimental data for forging-relevant conditions. Therefore, this study presents an experimental–numerical methodology for determining load-dependent HTCs representative for compound forging. A specialised test setup was used to reproduce the thermal–mechanical boundary conditions of hot bulk forming, by inducing contact pressures both below and above the flow stress of the workpiece material. Temperature histories were recorded using embedded thermocouples and analysed through an inverse numerical approach based on a one-dimensional (1D) finite element (FE) model. The influence of contact pressure, heating atmosphere, and lubrication on the HTC was systematically investigated for a S235JR specimen temperature of 600 °C. The results demonstrate a major pressure dependency of the HTC, whilst increasing for higher contact pressures. Oxide formation and lubrication were shown to significantly affect heat transfer behaviour, particularly while heating under atmospheric conditions. The presented approach provides process-specific HTC data that can substantially improve the predictive capability of numerical simulations for compound forging applications.

• Periodical: Materials Science Forum (Volume 1186)
• Pages: 1-11
• DOI: https://doi.org/10.4028/p-wwLq8G
• Online since: April 2026
• Authors: Norman Mohnfeld*, Marie Schute, Simon Peddinghaus, Johanna Uhe, Bernd Arno Behrens
• Keywords: Compound Forging, Experimental-Numerical Approach, Heat Transfer Coefficient

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