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

Abstract

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.

Mechanisms of subgrain coarsening and its effect on the mechanical properties of carbon-supersaturated nanocrystalline hypereutectoid steel

“…The dissolved carbon atoms were found to be http://dx.doi.org/10.1016/j.actamat.2014. 10.027 1359-6462/Ó 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.…”

“…During the past 50 years great efforts have been made to understand the microstructural evolution and its effect on strength upon cold drawing [3][4][5][6][7][8][9]. The most frequently reported finding is deformation-induced cementite decomposition [10][11][12][13][14][15][16][17][18][19] and its "unexpected" consequence on strain hardening, i.e. the decomposition of the hard phase-cementite-surprisingly does not adversely affect the material's strength.…”

“…Different from the assumption that the decomposition takes place upon cold drawing, due to the interaction between dislocations and carbon [3,18,19], Takahashi et al [21] suggested that it mainly occurs upon low-temperature aging after cold drawing. With the development of characterization techniques such as Mössbauer spectroscopy [10], field ion microscopy (FIM) [11,15,[22][23][24][25] and atom probe tomography (APT) [12][13][14][15][16]18,19] a deeper understanding of the mechanisms of cementite decomposition and their effects on microstructure and strength has been achieved. Among these characterization techniques APT is able to provide nanoand atomic-scale information on the carbon distribution in both cementite and ferrite with high compositional accuracy and statistical significance [2,19].…”

Partially amorphous nanocomposite obtained from heavily deformed pearlitic steel

“…Thus, the microstructural evolution of cold-deformed pearlitic steels has been, for many years, a topic of considerable scientific research, see, e.g. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. In this context, the dissociation of cementite upon plastic deformation has been discussed for some time [2][3][4][5]18,21,22].…”

Measurement of Dynamic Strain Aging in Pearlitic Steels by Tensile Test.

“…1,2,5) The strain-induced decomposition of cementite was first detected by Belous and Cherepin 8) in 1961. The amount of decomposed cementite in deformed Fe-C alloys was estimated by Gridnev et al 9) using Mossbauer spectroscopy. Several studies, in which various experimental techniques were employed, [10][11][12][13][14] gave further evidence of cementite decomposition during plastic deformation of pearlite.…”