Creep mechanisms and cavitation of AA5052 at intermediate stress and temperature region

Abstract

Creep mechanism and cavitation of AA5052 were studied employing creep experiments at 200–350°C and stresses 15–70 MPa. The microstructural observations were then performed to assess grain growth and formation of cavities. The apparent activation energy was defined in a range of 154–166 kJ/mole. It was found that at higher normalised stress region ( $\sigma /G>2.5\times {10}^{-3}$ ), the stress exponent was about 7 and at lower stresses it decreased to about 5. Microstructural instability, that is, grain growth, was detected during creep at a temperature of 300°C or higher. This phenomenon affected the strain rate and the governing mechanisms. Microstructure of the sample tested at 300°C revealed that the coalescence of cavities could occur at creep strains higher than 6.5%.