Features of changes in the strength properties of iron-based alloys in the temperature range of magnetic transitions

• V.A. Dotsenko. Vladivostok State University of Economics and Service. Vladivostok. Russia.

• Belous I.A.

  I.A. Belous. Vladivostok State University of Economics and Service. Vladivostok. Russia

The purpose of this work is to study the features of changes in the strength properties of Febased  alloys  in  the  temperature  range  of  magnetic  transitions.  Iron-manganese  and  ironnickel alloys in the most widely used concentration range (20-25%) for manganese and (28-42%) for nickel were chosen as materials for this study. In addition, studies were conducted on metals and alloys directly used in industry – nickel, armco iron, Fe-3% Si, Fe-25% Cr. Samples were quenched from 1050 ° C in water for Fe-Mn alloys; for Fe-Ni, Armco-Fe, nickel was annealed in vacuum at 1000 ° C for 1 hour. In order to study the effect of the magnetic transformation in the γ phase (austenite) on the strength properties of the alloys unstable during cooling, the sample was heated in an IMASH-50-65 unit at a rate of 50 K / min above T ε → γ for Fe-Mn and higher T → γ for Fe – Ni alloys, held for 20 min and then cooled to the required test temperature. After that, stretching was carried out under isothermal conditions at a rate of 4.4 ∙ 10-4 m • s-1. An investigation of the temperature dependence of the strength and plastic properties indicates their anomalous change in the temperature range of mag-
netic  transitions  “paramagnetism-ferromagnetism”,  “paramagnetism-antiferromagnetism”.  The  anomaly of  the  strength properties  and plasticity  under  magnetic  ordering is due to the appearance of an additional magnetic component in the Peierls force below the magnetic ordering temperature; the presence of the alloy of a large magnetovoltage  effect;  instability  of  the  crystal  lattice  during  the  magnetic  transition. It is assumed that in the initial paramagnetic phase of the Fe-Mn alloy, when approaching the Nйel point, a region of near magnetic order is formed, in this case antiferromagnetic clusters, which in turn, through magnetostriction stresses, contribute
to the martensitic transformation under the influence of a magnetic field.
Keywords: Fe-Mn alloys, austenite, magnetic alteration, strength properties.