In-situ neutron diffraction study on the tension-compression fatigue behavior of a twinning induced plasticity steel

Evolution of the peak intensity for different grain orientations was in-situ measured by neutron diffraction for a twinning induced plasticity steel during tension-compression fatigue tests. Amplitude of the intensity variation is larger in high cycles than that at early cycles. The hysteresis loop features an asymmetric shape at early cycles and becomes symmetric with increase of cycles. Different twinning/detwinning activities correspond to different shape of the hysteresis loop. In cycle one, limited fresh twin volume is expected to correspond to short period of detwinning/retwinning. At later cycles, the twinning and detwinning are expected to happen together throughout the whole cycle. Obvious peak intensity change due to twinning/detwinning in cyclic loading on the present TWIP steel was in-situ observed from the neutron diffraction data. The miscrostructure after 1000 cycles is given by the EBSD image quality (IQ) picture [Display omitted]