In recent years, the major trend in sheet metal forming is represented by the increase of strength/mass ratio of components for lightweight constructions and automotive industry. One way to achieve this target is weight reduction of structural part using High Strength Steels (HSS), which allows reducing the thickness of sheet components and maintaining safety requirements and mechanical strength. Compared with conventional sheet metalforming, the proper design of hot stamping process chains requires the deep knowledge of both interface phenomena and material behaviour at high temperatures in order to obtain the desired properties of final products in term of microstructure and strength characteristics, combining the advantages of better formability at high temperatures, lower springback and increase in the quality of formed parts. The work presented in this paper is part of a research project, which aims to develop a general approach that will be able to offer accurate models to correlate process parameters in hot stamping with the mechanical behaviour of the formed component during its service life. This paper focuses on the part of the approach that is devoted to develop a new experimental set-up, based on Nakazima test, to obtain FLD at elevated temperatures. In the design of the test, experimental and numerical techniques are used for the investigation, combining: − identification of the CCT curves for reliable prediction of microstructure; − heating and cooling tests for the optimization of microstructure evolution and; −a fully coupled thermal and mechanical FE model of the workpiece and tooling during the process. In the first part of the paper, the main features of the approach are outlined. Details on the experimental and numerical techniques are then given with the description of the apparatus and the main results of experimental tests carried out on the 22MnB5 high strength steel.

Testing Material Formability In Hot Stamping Operations

GHIOTTI, ANDREA;BRUSCHI S.
2006

Abstract

In recent years, the major trend in sheet metal forming is represented by the increase of strength/mass ratio of components for lightweight constructions and automotive industry. One way to achieve this target is weight reduction of structural part using High Strength Steels (HSS), which allows reducing the thickness of sheet components and maintaining safety requirements and mechanical strength. Compared with conventional sheet metalforming, the proper design of hot stamping process chains requires the deep knowledge of both interface phenomena and material behaviour at high temperatures in order to obtain the desired properties of final products in term of microstructure and strength characteristics, combining the advantages of better formability at high temperatures, lower springback and increase in the quality of formed parts. The work presented in this paper is part of a research project, which aims to develop a general approach that will be able to offer accurate models to correlate process parameters in hot stamping with the mechanical behaviour of the formed component during its service life. This paper focuses on the part of the approach that is devoted to develop a new experimental set-up, based on Nakazima test, to obtain FLD at elevated temperatures. In the design of the test, experimental and numerical techniques are used for the investigation, combining: − identification of the CCT curves for reliable prediction of microstructure; − heating and cooling tests for the optimization of microstructure evolution and; −a fully coupled thermal and mechanical FE model of the workpiece and tooling during the process. In the first part of the paper, the main features of the approach are outlined. Details on the experimental and numerical techniques are then given with the description of the apparatus and the main results of experimental tests carried out on the 22MnB5 high strength steel.
2006
Drawing the things to come: trends and advances in sheet metal forming; IDDRG International Deep Drawing Research Group 2006 conference
9728953062
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2441977
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