Interaction between hydrogen and a nitrided layer

• Autorzy: Ćwiek J.
• Języki publikacji: EN

Abstrakty

EN

Purpose: of this paper is to reveal the influence of nitrided layer on 34CrAlNi7-10 steel to its susceptibility to hydrogen degradation. Investigation was carried out with the use of slow strain tensile rate test (SSRT). Design/methodology/approach: Nitriding was done in the nitrogen-hydrogen (or argon) gas atmospheres with various hydrogen content, i. e. 0%, 30%, and 70%, at the glow discharge at temperature 560°C for 6 hrs. In order to estimate the degree of hydrogen degradation SSRT test was conducted on round smooth specimens 4 mm in diameter. Tests were performed at ambient temperature either in dry air or in 0.005 M H₂SO₄ solution. The applied strain rate was 10^-6 s^-1. Tests in acid solution were conducted under cathodic polarization with constant current densities: 0.1; 1; 5 and 10 mA/cm². Fracture surfaces after SSRT test were examined with scanning electron microscope (SEM) to reveal a mode and mechanism of cracking. Findings: Plasma nitrided layers are effective barriers to hydrogen entry into structural steel which decreases susceptibility of steel to hydrogen degradation. Hydrogen is mainly accumulated in a compact nitrides zone. Evidences of no increase in brittleness of nitrided layers with absorbed hydrogen were observed. Research limitations/implications: There is no possibility to perform direct observations of exact mechanism of hydrogen-assisted cracking so far. Further research should be taken to reveal the exact mechanism of increased plasticity of nitrided layer with absorbed hydrogen. Practical implications: Plasma nitrided layers are effective barriers to hydrogen entry into structural steel utilized in aggressive environments, which could be potential sources of hydrogen charging of exploited steels. Originality/value: Plasma assisted nitriding provides the formation of thin compact nitride zone which protects high-strength steels against corrosion and hydrogen degradation. Evidences of no increase in brittleness of nitrided layers with absorbed hydrogen were observed.

Słowa kluczowe

EN

corrosion; hydrogen degradation; nitrided layer; hydrogen permeation and uptake

• Wydawca: International OCSCO World Press
• Czasopismo: Journal of Achievements in Materials and Manufacturing Engineering
• Rocznik: 2011
• Tom: Vol. 47, nr 1
• Strony: 34--41
• Opis fizyczny: Bibliogr. 20 poz., rys., tab.

Twórcy

autor

Ćwiek J.

• Institute of Engineering Materials and Biomaterials, Silesian University of Technology, ul. Konarskiego 18a, 44-100 Gliwice, Poland

Bibliografia

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