Failure Modelling and Experimental Evaluation of a Press-Hardened Laboratory Scale Component with Multi-Phase Microstructure

Proceedings

Document identifier: oai:DiVA.org:ltu-75739
Keyword: Engineering and Technology, Mechanical Engineering, Applied Mechanics, Teknik och teknologier, Maskinteknik, Teknisk mekanik, Solid Mechanics, Hållfasthetslära
Publication year: 2019
Abstract:

Hot stamping of boron alloyed steel has become a standard in the automotive industry for safety relevant body in white components. This process allows the design of complex geometries with superior mechanical properties. Special tool design enables to manufacture components with special properties based on varying microstructures in designated areas. This is a challenge for finite element (FE) simulations of deformation and failure for multi-phase microstructure components.

In the present work, a laboratory scale test component with multi-phase microstructure is studied from blank to fractured component. Using different tool temperatures and adding an air-cooling step before transfer to the press hardening tool, the microstructure of the component is varied. By this, components with four different multi-phase microstructures are produced. These components are tested under tensile deformation until fracture, where force, elongation and the strain field on the components surface are measured.

The laboratory scale test component is evaluated using FE-modelling. The complete production process is modelled starting with the pre-cut austenitized blank, subsequent transfer, air-cooling, forming operation, and the final post-cooling. The resulting multi-phase micro structures are evaluated using manual optical microscope image analysis and compared with the simulated phase composition. Furthermore, the deformation and fracture of the manufactured component under tensional loading is studied using a mean-field homogenization scheme for the multi-phase composition combined with the OPTUS failure model. This finite element investigation is conducted taking the microstructure composition, shape and thickness deviations from the forming simulation into account.

The present work shows the feasibility of modelling methods of the complete process chain for press-hardened components with multi-phase microstructures, from blank to fractured component.

Authors

Stefan Marth

Luleå tekniska universitet; Material- och solidmekanik
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Stefan Golling

Gestamp R&D, Box 828, 97 125 Luleå, Sweden
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Rickard Östlund

Gestamp R&D, Box 828, 97 125 Luleå, Sweden
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Anna Barrero Pijoan

Eurecat, Centre Tecnològic de Catalunya, Unit of Metallic and Ceramic Materials, Plaça de la Ciència 2, 08243 Manresa, Spain
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Hans-Åke Häggblad

Luleå tekniska universitet; Material- och solidmekanik
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Mats Oldenburg

Luleå tekniska universitet; Material- och solidmekanik
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