Analysis of Dislocation Structures in Ferritic and Dual Phase Steels Regarding Continuous and Discontinuous Loading Paths
In sheet-bulk metal forming processes the hardening behavior of the material depends on the sequence of deformation steps and the type of deformation. Loading path changes induce transient hardening phenomena. These phenomena are linked to the formation and interaction of oriented dislocation structures. The aim of this study is to investigate the effect of continuous and discontinuous loading path changes on the dislocation microstructure in ferritic and ferritic-martensitic dual-phase steel, respectively. For the experiments a biaxial test stand was used, which permits to continuously change the load from tension to shear. In the ferrite single-phase steel transmission-electron microscopy reveals a reduced evolution of oriented dislocation structures for continuous loading path changes compared to discontinuous loading path changes. This evolution is further decreased in dual-phase steel compared to the ferritic steel. Microstructural results for the ferritic steel are accompanied by simulation results with a transient hardening model.
KeywordsSheet-bulk metal forming Dislocation structures Material modeling Parameter identification
Funding by the German Research Foundation (DFG) within the scope of the Transregional Collaborative Research Centre on sheet-bulk metal forming (SFB/TR 73) in the subproject C4 ‘Analysis of load history dependent evolution of damage and microstructure for the numerical design of sheet-bulk metal forming processes’ is highly acknowledged.
- 7.M. van Riel, Strain path dependency in sheet metal-experiments and models. Ph.D. Thesis, Twente University, Enschede, The Netherlands, 2009Google Scholar
- 12.Behrouzi et al., Inherent and induced anisotropic finite visco-plasticity with applications to the forming of DC06 sheets. Int. J. Mech. Sci. 89, 101–111 (2014)Google Scholar
- 16.K. Isik et al., Evaluation of Void Nucleation and Development during Plastic Deformation of Dual-Phase Steel DP600. Steel Res. Int. 87, (2016). doi: 10.1002/srin.201500483
- 17.T. Clausmeyer, Evolution of plastic anisotropy in metals: Material models, experiments and applications. Diss., Fakultät Maschinenbau. Technische Universitaet Dortmund (2016)Google Scholar