SHIFT - Semi-Hot Integrated Forming for TRIP-aided Steels

To ensure smooth project progress, the consortium is meeting up at regular intervals. By continuous updating and communication, upcoming issues and risks are identified and mitigated as early as possible.

As one of the first steps, the TRIP-aided steel chosen in the consortium will be tested. This includes mechanical and microstructural testing as a baseline measurement. Moreover, important metallurgical parameters regarding the phases such as martensite and austenite are are determined.

Based on most recent research publications and literature, the consortium will propose possible semi-hot process routes. The various temperature points, heating-/cooling-rates, holding times, etc. will be determined using a dilatometer. These investigations will include the integrated galvannealing process step.

The process parameters of WP3 will be used to prepare the first trial runs of semi-hot forming on a lab-scale forming press. Depending on the required heating rates and temperatures, a suitable induction heating setup will be prepared. It is important to ensure homogeneous temperature within a certain pre-cut metal sheet.

Verification of correctly applying all relevant parameters is achieved by extracting samples from the semi-hot formed parts and comparing them to "ideally" treated samples based on the dilatometric tests.

Two generic geometries will be used: A simple U-shaped profile as well as a 3-dimensionally curved, complex part representing a generic car body structure part.

Based on the previous findings, the forming tools will be designed and manufactured, ensuring compliance with required process parameters. This will require temperature-controllable forming tools and respective cold forming tools for comparison.

Using the forming tools of WP5, try-out runs and manufacturing of the respective demonstrator parts are conducted. Especially the geometrical comparison between semi-hot and cold formed parts will show the achieved improvements regarding springback and geometric distortions. Finally, based on samples from the demonstrator parts, all properties will be verified: Mechanical testing to verify strength and ductility; Microstructure testing to ensure the retained austenite required for TRIP is still present; Coating/LME testing to verify the effectiveness of the integrated galvannealed coating.

Demonstrator parts of WP6 are checked for LME-induced cracking due to the forming process. Since the produced parts need to be spotwelded, a parameter study will be conducted to find optimal welding parameters and simultaneously determine how effective the GA coating is against LME. Additional corrosion resistance testing will conclude this workpackage.

Using semi-hot formed samples, all necessary parameters for detailed FE-simulation are determined. The simulation is focused on crashworthiness, which is accompanied by parallel real-world testing of the demonstrator parts. This allows for detailed assessment of their deformation behavior and crashworthiness.

Finally, based on the developed process route and achievable improvements, ecological and economic implications of implementing this process in car parts production will be assessed.