WEB In-situ investigation on deformation behavior of Cu-alloyed medium-Mn steels by high energy synchrotron X-ray diffractionTuesday (22.09.2020) 15:15 - 15:30 S: Structural Materials 1 Part of:
As a promising candidate within the 3rd generation advanced high strength steel grades, medium manganese steels (MMnS) have drawn more and more attention in the last years because of its outstanding strength and formability. The excellent combination of strength and ductility is mainly achieved by proper adjustment of the microstructure and partitioning features during austenite-revert-transformation (ART) annealing. Recently, Cu-alloying have become a new alloy design approach to improve the mechanical property of the MMnS steels, due to the fact that it may effectively adjust the stacking fault energy (SFE) of austenite to tune the deformation mechanisms and/or precipitate within ferrite during ART annealing to increase the yield strength by precipitation strengthening.
In the present work, high energy synchrotron x-ray diffraction was applied in an in-situ regime to investigate the deformation behavior of the Cu-alloy MMnS steels. The phase transformations during deformation in Fe-0.05C-7Mn-1.5Al-1.5Si-1.5Cu-1.5Ni-0.5Mo steel was tracked with the aid of synchrotron X-ray diffraction at beamline P02.1 at DESY, Hamburg. The investigated Cu-alloyed MMnS steels were ART annealed at different temperatures to investigate its effect on the mechanical property. Quantitative microstructure analysis was carried out by using Rietveld refinement method. The results show that higher ART annealing temperature promoted higher volume fraction yet lower deformation stability of retained austenite. Besides, the ART temperature influences the onset sequence of plastic deformation stage for austenite and ferrite phases. Higher ART temperature recovers the accumulated dislocation of ferrite phase, leading to a different elastic-plastic deformation transition behavior. The ART annealing temperature plays a key role in tailoring the phase transformation and deformation behavior of Cu-alloyed MMnS. Furthermore, the strain partitioning during deformation of the investigated steels was further discussed in detail.