The Mössbauer effect was studied in cold‐deformed Fe–C alloys. Plastic deformation leads to a significant intensity decrease of the Fe57 lines in the cementite due to the decomposition of the latter and to the transition of iron and carbon atoms into ferrite. The broadening of ferrite lines is observed but this effect is found to be much weaker than theoretically previewed. Carbon atoms situated in ferrite after cementite decomposition form atmospheres around dislocations and thus cause an additional NGR spectrum with a large isomeric shift and quadrupole splitting from iron atoms which are the nearest neighbours of the carbon atoms on dislocations. Heating of deformed alloys results in the weakening of bonding between dislocations and carbon atoms and leads to cementite recovery. The latter process is observed to become intensive at heating above 400 °C (the temperature of impure atmosphere condensation around dislocations in α‐iron). The increase in the heating rate inhibits the process of cementite recovery and helps to preserve the marked concentration of carbon atoms on dislocations in ferrite up to the temperature of the α → γ transformation. According to evaluations the impurity atmospheres around dislocations in cold‐deformed Fe–C alloy may contain more than ten carbon atoms per plane of atoms.

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.

The effect of the alloying elements on the cementite decomposition during the steel plastic deformation is studied by means of the NGR technique. The decomposition is shown to be governed by the competition between the binding energy of the carbon atoms to the dislocations in ferrite and the cementite solution heat. Among the elements under consideration vanadium and nickel suppress the cementite decomposition most effectively. The alloying elements distribution among the G‐ and S‐sites of the cementite lattice is inhomogeneous. The G‐sites are occupied predominantly by the elements that reduce the carbon chemical potential in the iron compounds (V, Mo, Mn) and the S‐sites – by those increasing it (Si). The plastic deformation changes the ratio of the alloying atoms populations of the G‐ and S‐sites in the residual cementite.

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