Shenawy, Eman; El-Shenawy, Eman; Tabakova, Bozhana; Табакова, Божана рец.; Шенауи, Еман; Ел-Шенауи, Еман

Nb-addition and cold deformation effects on corrosion resistance of type 304L austenitic stainless steel

Ефекти на корозия под напрежение на аустенитна неръждясваща стомана – 304L при обогатяване с ниобий и след студена деформация

2005

PROCEEDINGS OF THE TECHNICAL UNIVERSITY - SOFIA, 55, 2005 - Anniversary “Sixty Years Technical University - Sofia”, pp. 323-335

TU - Sofia

0374-432Х [issn]

Article

eng

steel - tests; стомана - изпитване

The effects of Nb addition and cold deformation (CD) on the electrochemical behavior of austenitic stainless steel were studied in 3.5% NaCl solution. Electrochemical impedance spectroscopy (EIS) measurements have been used to investigate the corrosion behavior after two weeks of the steel immersion in 3.5% NaCl solution. The occurrence of localized corrosion was examined by visual inspection and scanning electron microscope (SEM). The energy dispersive spectrometry (EDS) analytical system was also used for qualitative analyses. XRD analysis was used to identify the chemical composition of the thin passive film formed at the material surface. According to EIS measurements, the corrosion resistance increased by increasing the Nb-content. XRD revealed presence of Cr-rich thin film as a result of increasing the Nb-content. Moreover, CD has a critical effect on the corrosion resistance. The specimen with the highest Nb-content (1.24 % Nb) processed with 23% CD showed the best protection against corrosion. Increasing the CD above this limit affects negatively the corrosion resistance. On investigation the Cr stabilization in welded pecimens, it was concluded that no negative corrosion resistance changes at the heat affected zone (HAZ) was noticed. This may be due to Nb addition.

Reviewer prof. B. Tabakova. - App. graphics and ill, pp. 330-335. - References, pp. 328-329