| 1. |
- Parareda, S., et al.
(författare)
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Effect of heat treatment conditions on the fatigue resistance of press hardened 22MnB5 steel evaluated through rapid testing technique
- 2021
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Konferensbidrag (refereegranskat)abstract
- Fatigue strength is considered as a crucial parameter for automotive applications subjected to cyclic loads during their long service life, as chassis parts. The high yield stress of press hardened steels poses them as good candidates for lightweight solutions with improved fatigue resistance. However, their high strength leads to an increase in notch sensitivity which can ruin the whole part's integrity. This behaviour was observed in previous works on press hardened steels, where their high fatigue strength was significantly affected by the surface conditions and by heat treatment conditions. Nevertheless, press hardening steels are still good candidates to manufacture complex geometry parts reaching high performance.Aiming at increasing the existing knowledge on the fatigue behaviour of press hardened steels, this paper analyses the fatigue performance of boron steel (22MnB5) under different time austenitizing times. Fatigue resistance is evaluated using a novel rapid fatigue testing technique based on the stiffness evolution. The method permits a fast and reliable determination of the fatigue limit. Based on results obtained with this rapid testing method, the most suitable heat treatment to mitigate fatigue notch sensitivity and then achieving the best fatigue performance for chassis applications is discussed.
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| 2. |
- Pujante, J., et al.
(författare)
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Investigations into wear and galling mechanism of aluminium alloy-tool steel tribopair at different temperatures
- 2013
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Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 308:1-2, s. 193-198
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Tidskriftsartikel (refereegranskat)abstract
- Aluminium alloys show poor formability at room temperature, and the production of complex components requires a series of high temperature forming processes, such as warm and hot forging, extrusion and hot sheet metal forming. Forming aluminium in these conditions subjects the tools to severe adhesive wear and galling, leading to increased energy needs, shorter tool life, lower part quality and increased cost. In this work, the wear mechanisms generated by aluminium alloys on forming tools have been studied by means of linear reciprocating sliding tests. Aluminium alloy AA2017 balls were slid against DIN 1.2344 (AISI H13) tool steel samples with various surface finishes at temperatures up to 450 °C. The main results show that the observed wear mechanisms are extremely dependent on the system temperature, ranging from pure abrasive wear to formation of layers of compacted aluminium debris and gross aluminium transfer in the form of lumps. On the other hand, tool surface finish has a limited effect on gross material transfer, but does affect the material transfer micromechanisms
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| 3. |
- Pujante, J., et al.
(författare)
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Microstructural and mechanical study of press hardening of thick boron steel sheet
- 2017
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Ingår i: Journal of Physics, Conference Series. - : Institute of Physics (IOP). - 1742-6588 .- 1742-6596. ; 896
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Tidskriftsartikel (refereegranskat)abstract
- Press hardening has become a staple in the production of automotive safetycomponents, due to the combination of high mechanical properties and form complexity itoffers. However, the use of press hardened components has not spread to the truck industrydespite the advantages it confers, namely affordable weight reduction without the use of exoticmaterials, would be extremely attractive for this sector.The main reason for this is that application of press hardened components in trucks impliesadapting the process to the manufacture of thick sheet metal. This introduces an additionallayer of complexity, mainly due to the thermal gradients inside the material resulting inthough-thickness differences in austenitization and cooling, potentially resulting in complexmicrostructure and gradient of mechanical properties.This work presents a preliminary study on the press hardening of thick boron steel sheet.First of all, the evolution of the sheet metal during austenitization is studied by means ofdilatometry tests and by analysing the effect of furnace dwell time on grain size. Afterwards,material cooled using different cooling strategies, and therefore different effective cooling rates, isstudied in terms of microstructure and mechanical properties. Initial results from finite elementsimulation are compared to experimental results, focusing on the phase composition in throughthickness direction.Results show that industrial-equivalent cooling conditions do not lead to gradientmicrostructures, even in extreme scenarios involving asymmetrical cooling.
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