Effect of the size and shape of cementite particles on the structure and properties of deformed steel

Conclusions

The shape of cementite particles has a considerable effect on the structure of deformed steel and its mechanical properties. The fine structure of ferrite resulting from plastic deformation of steel with globular cementite is similar to the structure of deformed carbon-free iron. Their dislocation structures are also similar. The shape, size, and internal structure of cementite crystals change little during plastic deformation (up to 50%). The strengthening of steel resulting from deformation is independent of the concentration of carbon and is the same as in carbon-free iron.

Plate-like cementite, unlike globular cementite, favors the creation of a more dispersed ferrite substructure as the result of deformation. Also the cementite crystals become plastically deformed, and as a result a fine structure is created within the crystals. Most of the eutectoid grains are broken up during deformation, and as the result the plate-like structure is destroyed. In regions where the plate-like structure is preserved the cementite becomes finer and the distance between the platelets decreases. The finer the structure of the eutectoid before deformation the greater this effect. An increase of the dispersity of the eutectoid favors a more developed fine structure of ferrite and cementite as the result of deformation.