Enhanced true stress-true strain relationships due to grain refinement of a low-carbon ferrite-pearlite steel

The fine-grained low-carbon ferrite-pearlite (FP) steel with the ferrite grain size of 3.6 mu m showed enhanced true stress (sigma) true strain (epsilon) relationships up to fracture, i.e., the plastic deformation limit. Both sigma and epsilon increased with decreasing ferrite grain size in the FP steels. The effect of ferrite grain size on the sigma-epsilon relationships up to the plastic deformation limit was dependent on the microstructure, in spite of belonging to the same low-carbon steel. In the FP steels, the smaller the pearlite size became with decreasing ferrite grain size, the more the pearlite could deform. The decrease in not only the ferrite grain size but also the secondary microstructure is effective in improving the sigma-epsilon relationship up to the plastic deformation limit. (C) 2015 Elsevier B.V. All rights reserved.