In situ neutron diffraction during tensile deformation of a ferrite-cementite steel

A fully pearlitic steel (specimen P1) was subjected to cold-drawing (P2) followed by aging at 423 K (P3) or 673 K (P4). Some drawn samples were annealed to make cementite particles spherical (P5). By using neutron diffraction, high compressive residual stress component parallel to the drawing direction was detected in the ferrite matrix of specimen P2, whereas this stress level was partly relaxed in P3 and mostly in P4. In situ neutron diffraction experiments performed during tensile tests have revealed different work hardening behaviors in these specimens. Based on the data provided by a profile analysis of diffraction spectra, i.e. microstrain related to dislocation density and block size, strength and work-hardening of these specimens are discussed. In particular, it is documented that the treatment of the specimen P4 which is equivalent to commercially Zn-plated steel wires produces the largest internal stress by tensile deformation leading to a good balance of strength and uniform elongation.