Diffractional Analysis of the Process of Electroimpulse Supression of Fatigue 
Failure of Steels 
S.V. Konovalov!, V.V. Kovalenko', V.V. Tsellermaer', O.V. Sosnin', S.N. Gorlova', YuF. 
Ivanov’, E.V. Kozlov?, V.E. Gromov! 
1 — Siberian State Industrial University, Novokuznetsk, Russia 
2 — Tomsk State University of Architecture and Construction, Tomsk, Russia 
The change of structure, phase composition and failures of steel 08X18H10T (C<0.08%, Cr<18%. 
Ni<10%, Ti<1%) subjected to low-cycle fatigue has been studied by methods optic, rastered and 
transmission electron diffracting microscopy on mesolevel. The reasons of resource increase and 
suppression of fatigue failure by electroimpulse treatment in a moment of transition to the third 
critical stage of the dependence of ultrasound speed on a number of cycles loading have been found 
out. An attention is paid to processes course of collecting recristallization, kinetics change of self- 
organization of the dislocation substructure and twinning and initiation of hard solution decay. 
The problem of the fatigue failure of steels and alloys is actual now inspite of its long history of 
research {1-5}. It is connected with that, many constructions and products of crucial purpose are 
used in such modes, but their failure occurs suddenly without marked previous signs. The latest 
works underlining the complex nature of fatigue phenomenon, connect the development of fatigue 
failures with self-organization of inner — and interstructural levels of plastic deformation. The 
deforming solid being unbalanced synergetic system, tends to include the maximum effective 
dissipation canals of energy. 
According to modern notions the fatigue failure is connected with mesoscopic substructure. Here, in 
places of the localization of plastic deformation the powerful mesoconsentrators of stresses causing 
the inclusion of mesoscopic mechanism of deformation. 
The failure is the final stage of mesostructure evolution, appearing after exhaustion by material of 
its accomodation possibilities. The ultrasound method of diagnos of the critical stages of 
approaching the fatigue failures has been offered by us earlier when the abrupt fall is noted on the 
curve of dependence of the ultrasound velocity v on a number of the cycles of N loading. The long 
preparatory stage of process with small gradual collection of microfailures precedes to this. For 
preventing the fatigue failures it is necessary to suppress the nucleation of mesoscopic substructure 
and to make weak its spreading through the material on account of lowering the rate of deformation 
localization and inadmissing the formation of mesoconsentrators of the stresses. It may be reached 
by treatment of materials with the help of powerful current impulses of optimum parameters 
according to frequency, amplitude and time of action. The important in this scheme is that, the 
maximum effect of increasing the resource of endurance in different steels up to 20-30% is 
achieved in electroimpulse treatment at a critical stage v(N). 
In initial state the analysed steel has the anisotropic grains (coefficient of anisotropy is 4,1), the 
medium size of which is 16 microns. It is characterized by traditional set of dislocation 
substructures formed as a result of preparatory thermomechanical treatment: there are the grains 
containing the chaotically spreaded dislocations (dislocation chaos) and the grains having a well- 
regulated dislocation substructure, i.e. a latticed and a fragmented substructure. Here, the 
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