| 1. |
- Garcia-Llamas, Eduard, et al.
(författare)
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Optimization of Thick 22MnB5 Sheet Steel Part Performance through Laser Tempering
- 2023
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Ingår i: Metals. - : MDPI. - 2075-4701. ; 13:2
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Tidskriftsartikel (refereegranskat)abstract
- Press Hardening offers the possibility to obtain a wide range of mechanical properties through microstructural tailoring. This strategy has been successfully applied in thin sheet components, for instance, through differential cooling strategies. The application of these added value features to truck components implies adapting the process to the manufacture of thick sheet metal. This introduces an additional layer of complexity, but also opportunity, in a process where the final microstructure and, thus the mechanical performance is generated in the press shop. This work presents a study on optimizing the crash worthiness and impact energy absorption on a press hardened thick 22MnB5 steel sheet. Different microstructure design strategies have been studied, including ferrite-Pearlite (representative of a differential heating and austenitization strategy), in-die generated Bainite (representative of differential cooling) and Tempered Martensite (generated through laser tempering), keeping a fully hardened martensite as a reference condition. The material performance has been compared in terms of the monotonic properties, useful for anti-intrusion performance, and Essential Work of Fracture, a well-suited parameter to predict the crash failure behavior of high strength steels. The results show that laser tempering offers properties similar to Bainite-based microstructures and can be a successful replacement in components where the sheet thickness does not allow for the fine control of the in-die thermomechanical evolution.
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| 2. |
- Latorre, Núria, et al.
(författare)
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Forming of mechanically interlocked aluminium and carbon fibre reinforced polymer parts with complex geometry
- 2024
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Ingår i: Material Forming - ESAFORM 2024. - : Materials Research Forum LLC. ; , s. 1640-1649
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Konferensbidrag (refereegranskat)abstract
- Forming of aluminium-CFRP hybrid structures into complex shapes is key to decrease environmental impact in automotive industry. However, challenges such as preserving joint integrity after forming operations must be assessed. Therefore, the authors of this work have cold stamped hybrid aluminium-CFRP panels into omega shaped profiles with and without a mechanical interlocking joining technology. The effect of lubricant application, of the CFRP positioning (inside or outside the omega profile), and of the number of mechanical joints were studied. It was concluded that it is possible to cold stamp aluminium-CFRP prepreg panels even with mechanical joints into complex profiles when lubricant is used. Moreover, the position of the CFRP prepreg has a strong impact on the flange springback of the stamped part.
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| 3. |
- Pujante, Jaume, et al.
(författare)
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Hot Stamped Aluminium for Crash-Resistant Automobile Safety Cage Applications
- 2021
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Ingår i: Materials Science Forum. - : Trans Tech Publications. - 0255-5476 .- 1662-9752. ; 1016, s. 445-452
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Tidskriftsartikel (refereegranskat)abstract
- Hot stamping, also known as press hardening in the context of sheet steel, has steadily gained relevance in the automotive industry, starting off as a specialist application and turning into a staple technique in the production of safety cage products in little more than a decade. However, despite the weight reduction offered by martensitic steels, further improvement could be obtained by substituting these components by high-performance aluminium. In this regard, the very same process of hot stamping could be employed to attain the required combination of shape complexity and mechanical properties at a reasonable cost for mass-market application, if the limitations imposed by cycle time and process window could be overcome. In this work, the feasibility of hot stamping of 6000-series aluminium alloy sheet is studied, first in dilatometry experiments and later in semi-industrial conditions in a pilot facility. A cycle time shortening strategy is employed, and compared to the conventional thermal cycle in terms of implementation and obtained results. In addition to basic characterization, aluminium thus processed is studied in terms of fracture toughness, in order to obtain data relevant to crashworthiness that can be readily compared with alternative materials.
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| 4. |
- Pujante, Jaume, et al.
(författare)
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Wear Mechanisms in Press Hardening: An Analysis through Comparison of Tribological Tests and Industrial Tools
- 2023
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Ingår i: Lubricants. - : MDPI. - 2075-4442. ; 11:5
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Tidskriftsartikel (refereegranskat)abstract
- Press hardened components have become widespread in the automotive industry in structural and crash-resistant applications, thanks to the combination of the complex shapes and high mechanical properties obtained. However, the press hardening of coated boron steel results in severe adhesive-based wear, with tool maintenance being required in as few as 3000 cycles. The current industrial implementation of press hardening is defined to work around this phenomenon. While this aspect has been studied by different authors, most of the literature deals with laboratory-scale tribosimulators, leaving an open question into how this knowledge transfers to macroscopic effects on the industrial process. In this work, wear in press hardening is studied by comparing the results obtained in laboratory conditions with a pilot-scale line, and finally, with wear mechanisms observed on industrial tools. The aim of this study is to consolidate the current knowledge about the micro-mechanisms involved, and to understand to what extent the existing tests reproduce the actual mechanisms observed in the press floor. The results show how material transfer mainly happens as an accumulation of dust compacted into initial defects on the tool surface. Moreover, this mechanism is effectively reproduced in laboratory tribosimulators and pilot environments, showing a similar morphology to wear on industrial tools. The work sheds light on the underlying causes of wear, and its potential mitigation strategies.
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