Evaluation of toughness deterioration by an electrochemical method in an isothermally-aged N-containing austenitic stainless steel

• Published in: Materials characterization 2009-02, Vol.60 (2), p.119-124
• Main Authors: Saucedo-Muñoz, Maribel L., Lopez-Hirata, Victor M., Avila-Davila, Erika O., Melo-Maximo, Dulce V.
• Format: Article
• Language: English
• Subjects: AGING; Applied sciences; Austenitic stainless steels; AUSTENITIC STEELS; CARBIDES; Cross-disciplinary physics: materials science; rheology; CURRENT DENSITY; Electrochemical methods; ELECTROCHEMISTRY; Exact sciences and technology; FRACTURES; Isothermal aging; MATERIALS SCIENCE; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; PRECIPITATION; Solidification; TEMPERATURE RANGE 0065-0273 K; TEMPERATURE RANGE 0400-1000 K; TEMPERATURE RANGE 1000-4000 K; Toughness
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2008.07.007

This work presents the results of an evaluation of the deterioration of cryogenic toughness by means of an electrochemical method in a N-containing austenitic stainless steel (JK2) aged at temperatures of 700, 800 and 900 °C for times from 10 to 1000 min. The aging process at 700 and 800 °C caused the decrease in the Charpy V-Notch impact energy at − 196 °C because of the intergranular precipitation of carbides. Scanning electron micrographs of the Charpy V-Notch test specimens showed the presence of intergranular brittle fracture. The degree of sensitization was determined by the ratio of the maximum current density generated by the reactivation scan to that of the anodic scan, I r/ I a, using the double-loop electrochemical potentiokinetic reactivation test. The Charpy V-Notch impact energy decreased with increase in the I r/ I a ratio. This relation permits an estimate of the deterioration of cryogenic toughness due to thermal aging in this type of steel.