Positron Annihilation in Corroded Steels St20 and St3S

Abstract

The paper deals with examining the lifetimes of positrons emitted from 22 Na source in corroded St20 and St3S steels. Influence of the method of defecting the sample surfaces on the spectrum of positron lifetimes was investigated. Influence of temperature of initial annealing of samples, plastic deformation, electrolytic hydrogenation and corrosion in HCl vapors on trapping positrons in the examined steels was also determined.

The Influence of Magnetic Field on Annihilation of Positrons in Corroded Steel St-20

“…This was caused by the rise in the values of τ 1 , τ 2 , I 2 . These results fully confirm the conclusions presented in [7][8][9][10][11][12] and prove that corrosion processes at the first stage of corroding cause an appearance and development of defects in the close-to-the-surface layer. The values of lifetimes τ 1 and τ 2 for the sample corroding in an external magnetic field are the same, within the limits of error, as for the samples corroding outside it.…”

“…Since 1999 we have carried on investigations of positron lifetimes emitted from the 22 Na source positrons in iron, nickel, and some steels with corroded surface [7][8][9][10][11]. We proved that the values of defect component of the positron lifetime spectrum and its intensity for samples with electrochemically corroded surface depend on the time of corroding, as well as on the chemical and mechanical conditions in which the corrosion was taking place.…”

The Influence of a Magnetic Field on the Formation of Corrosion Defects in Selected Metals and Steels, Analysed Using Positron Annihilation Method

“…For samples (4) and (6), as the values of P b , we accepted those that were designated after magneting aging, but before corrosion.…”

Effect of magnetic field on the corrosion of iron and St20 steel as studied by positron annihilation

“…The results of many previous investigations ( e.g . 9–13) demonstrated that the corrosion‐induced changes in the parameters of the lifetime spectra of positrons annihilating in iron, nickel and steel depend on the corrosion time and environment, as well as on the state of the surface of corroding metal. After removing the several micrometers thick corroded layer, the positron annihilation parameters achieve values the same as before corrosion.…”