Laser assisted strategies for the manufacturing of property-enhanced Tailor Heat Treated Blanks

• Applicant: Professorin Dr.-Ing. Marion Merklein
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 386418429

The objective of the present research project consists of the identification and qualification of irradiation strategies for the production of Tailor Heat Treated Blanks (THTB) of high strength, precipitation hardenable aluminum alloys of the 7000 series. Based on conventional, linear-continuous heat treatment layouts for the manufacturing of THTB, new irradiation concepts will be derived in order to improve the homogeneity of the heat treated area with respect to shape distortion as well as material properties. This approach is based on a combined experimental-numerical methodology. In the first work package (WP) temperature-dependent material parameters are investigated. On the one hand the relevant input parameters for a thermo-mechanical coupled FE-model have to be determined at elevated temperatures. On the other hand mechanical properties after a short-term heat treatment have to be investigated in order to model the locally adapted flow behavior of THTB. These input parameters will be used for modeling in WP2. This approach is based on a two-step model. The thermo-mechanical effect of a laser heat treatment will be modeled numerically with respect to the resulting shape distortion as well as the distribution of material properties. A mechanical simulation model for forming processes will be developed, which considers the material flow behavior in dependency of temperature distribution and pre-straining. A FE-based calculation of variants will be carried out in the third WP using the validated FE model from WP2 to identify the influence of different quantitative as well as qualitative factors on the command variables of shape distortion and homogeneity of the heat treatment. New heat treatment strategies will be developed. The numerical results will be verified by experimental investigations. Based on these results a significance test to identify the most influencing factors will be carried out. The last work package focuses on the validation of the second step of the FE-model from WP 2 as well as the application of the model for the process design of THTB. Based on numerical and experimental results a local laser heat treatment will be carried out for a demonstrator geometry, followed by a deep-drawing process. The digitalization of the final part enables the experimental validation of the forming simulation as well as the comparison of different heat treatment concepts regarding the resulting component properties. The application of new irradiation concepts has to improve the properties compared to a conventional, linear-continuous laser heat treatment. The transfer of the general guidelines for the application of alternative heat treatment concepts from WP 3 on the demonstrator geometry enables the qualification of the results.

• DFG Programme: Research Grants