Investigation of carbide phase in strained steel by the method of nuclear gamma resonance

The Mössbauer effect was used to investigate the cementite state in cold-worked steel. An intensive dissociation of cementite is found at plastic deformation of the steel with the structure of plate perlite. For deformation of 93% this dissociation amounts to 50%. The effect of dissociation was not observed in the steel with granular perlite. The fact that cementite dissociates at deformation may be explained by the increase of bond energy between C atoms and dislocations as compared to that for carbon in the cementite lattice. Alloying with the elements which decrease the bond of dislocations and substitutional impurities has the result that the cementite becomes much more stable at deformation. This is shown on the example of steel containing cobalt. The latter fact influences strongly the mechanical properties of a cold worked steel.