View More View Less
  • 1 Higher Institute of Chemical Technology 1156 Sofia Bulgaria
Restricted access

Abstract  

A study on the composition of the surface films and corrosion products of mild and low-alloy (2% Cr) steels in 1M NaH2PO4 under stress-corrosion cracking (SCC) conditions has been carried out using Mössbauer spectroscopy. At potentials in the SCC region the films formed on both steels contain Fe3(PO4)2.4H2O, Fe3(PO4)2.8H2O and FePO4.xH2O. The precipitates in the solution formed under these conditions consist of FePO4.xH2O and iron(III) hydrogen phosphate [most probably Fe(H2PO4)3.2H2O]. An attempt has been made to relate the surface film composition to SCC susceptibility.