In situ neutron diffraction and crystal plasticity analysis on Q & P1180 steel during plastic deformation

Q&P1180 is a typical third generation of advanced high strength steel. In this paper, the microstructure evolution of the Q&P1180 steel during uniaxial tension is investigated comprehensively by using in situ neutron diffraction technique, electron backscatter diffraction (EBSD), scanning electron microscope (SEM) and the elastic-viscoplastic self-consistent with phase transformation (EVPSC-PT) model. Tempered martensite (TM) is determined as the matrix based on SEM and EBSD analysis. Tiny blocky retained austenite (RA) islands are distributed in the matrix, and transformed into martensite during deformation. Effects of phase transformation on the stress-strain response, lattice strains, diffraction intensities and texture evolution of the Q&P1180 are discussed based on experiments and the EVPSC-PT model. The progressive phase transformation from austenite to martensite is orientation-dependent, and the gamma{200} orientation has the lowest stability, followed by gamma{220} and gamma{311} orientations. The flow stress of each phase with straining shows that the strength of RA in Q&P1180 is higher than that of TM, due to its high carbon content.