The work hardening and the internal stress averaged in each constituent, so called “phase stress” in a pearlite steel were studied by means of neutron diffraction techniques, time-of-flight (TOF) and angler dispersion (AD) methods. The overall diffraction profiles obtained by the TOF method indicates that the cementite (122) and feirrite (110) peaks are preferable to be employed for the in situ neutron diffraction with the AD method during tensile testing. The stress partitioning between cementite and ferrite after the onset of plastic deformation is evidently found. Hence, the high work-hardening of the pearlite structure is demonstrated to be caused by the generation of phase stress. The influence of ferrite block orientation on the residual phase stress after tensile deformation is shown. Then, the heterogeneous plastic flow at several classes is speculated, which makes complicate to estimate the stress in each constituent from (hkl) lattice plane strains measured.
