Anion effects on the stress corrosion cracking behaviour of aluminium alloys

✍ Scribed by R. Braun

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: German
• Weight: 789 KB
• Volume: 54
• Category: Article
• ISSN: 0947-5117
• DOI: 10.1002/maco.200390035

✦ Synopsis

The stress corrosion cracking behaviour of plate material of the aluminium alloys 2024-T351, 8090-T8171, 7475-T651, and 7075-T7351 was investigated performing constant load tests. Short transverse tensile specimens were permanently immersed in aerated aqueous 0.6 M Na 2 Cl solutions with additions of Na 2 SO 4 , NaNO 3 , NaHCO 3 , NH 4 HCO 3 , Na 2 HPO 4 , Na 2 SO 3 or Na 2 CO 3 . The concentration of the added salts was 0.06 M. The applied stress was 100 MPa, except with 7075-T7351 specimens, which were loaded at 300 MPa. Environment induced failure was not observed in neutral 0.6 M NaCl solution. The various salts added promoted intergranular stress corrosion cracking with the alloys 2024-T351, 8090-T8171, and 7475-T651. Threshold stresses were generally below 100 MPa. For 8090-T8171 exposed to chloride containing electrolytes with additions of sulfate, hydrogen phosphate, or sulfite, threshold stresses were approximately 100 MPa or higher. Similar results were obtained for 7475-T651 plate when immersed in chloride-hydrogen phosphate and chloride-carbonate solutions. Alloy 7075-T7351 was resistant against intergranular stress corrosion cracking. Specimens suffered pitting corrosion during immersion in the corrosive environments. Failure observed with 7075-T7351, in particular when exposed to the chloride-nitrate solution, was associated with reduction of cross-sectional area due to pitting and transgranular stress corrosion cracking.

Das Spannungsrisskorrosionsverhalten von Plattenmaterial der Aluminiumlegierungen 2024-T351, 8090-T8171, 7475-T651 und 7075-T7351 wurde in kurzer Querrichtung untersucht. Dauertauchversuche wurden unter konstanter Belastung in wa Èssrigen 0,6 M