Effect of Load on the Corrosion Behavior of Friction Stir Welded AA 7075-T6 Aluminum Alloy

• Main Authors: Marina Cabrini, Sara Bocchi, Gianluca D’Urso, Claudio Giardini, Sergio Lorenzi, Cristian Testa, Tommaso Pastore
• Format: Article
• Language: English
• Published: MDPI AG 2020-06-01
• Series: Materials
• Subjects: corrosion; stress-corrosion cracking; friction stir welding (FSW); AA7075
• Online Access: https://www.mdpi.com/1996-1944/13/11/2600

The paper focuses on the corrosion behavior of aluminum joints made by friction stir welding as a function of loading conditions. A four-points bend-beam test, constant loading test, and slow strain-rate test were carried out on AA 7075-T6 alloy in aerated NaCl 35g/L solution at room temperature monitoring the free corrosion potential. The penetration depth of the intergranular attack was deeper after the four-point bent-beam tests compared to all the other testing techniques. Preferential dissolution along the grain boundaries was found in the heat-affected zone and the attack follows the elongated grains structure along the rolling direction. However, no stress-corrosion cracking phenomena were detected. No relevant stress corrosion cracking (SCC) crack embryos propagation was noticed under uniaxial tensile tests—both constant loading and slow strain-rate tests—manly due to the high dissolution rate occurring at the crack tip which promoted premature shear ruptures.