Characterization and methodology for calculating the mechanical properties of a TRIP-steel submitted to hot stamping and quenching partitioning (Q&P)
E.A. Arizaa.b., A.S Nishikawaa, H. Goldensteina, A.P. Tschiptschina.b.
- Metallurgical and Materials Engineering Department – University of São Paulo
- Brazilian National Nanotechnology Laboratory – CNPEM
Research conducted at LNNano/CNPEM was recently published at Materials Science and Engineering: A. Researchers used a series of advanced techniques in order to better understand the mechanical behavior of a TRIP-steel. Techniques included the use of the in situ X-ray diffraction thermomechanical simulation facility XTMS, available for external users since 2013. This research project was supported by CAPES, CNPq and FAPESP.
Thermomechanical simulation of quenching, hot stamping, and quenching and partitioning processes of a high-strength TRIP-assisted steel were carried out in a Gleeble®3S50 thermo-mechanical simulator, coupled to the synchrotron X-ray diffraction line. The microstructures and mechanical properties were analyzed using Field Emission Gun Scanning Electron Microscopy (FEG-SEM), X-ray diffraction, and nanoindentation. The microstructures of thermomechanical treated specimens were modeled using the Object Oriented Finite Element (OOF) technique. The modeled microstructures were then fed into a finite element model to predict the mechanical behavior. By using a reverse algorithm method, the elasto-plastic mechanical properties of different microconstituents were determined. This was done through the analysis of instrumented nanoindentation loading-penetration curves. Tensile properties of the thermomechanical processed steels were measured by tensile testing of subsized specimens cut from samples processed on the Gleeble®3S50. The comparison between the experimental results and those of the reverse algorithm and the OOF modeled microstructure showed quite good agreement.
(a) Microstructure of TRIP steel treated in the Gleeble 3S50 thermomechanical simulator coupled to the Synchrotron X-ray diffraction line. (b) Filtering and segmentation of images for detecting phases and microconstituents (c) Object Oriented Finite Element technique used to predict the mechanical behavior of the thermomechanical treated alloy (d) In situ X-ray diffraction patterns of the four thermomechanical conditions (e) Predicted hardness variation across the microstructure (f) Predicted tensile strength of microconstituents.