Cellular automata simulation of cavity growth during creep of Al–Mg alloy

Abstract

Lifespan of high temperature services could seriously be affected by cavitation and thus, prediction of this phenomenon is considered as a significant task. A two-dimensional cellular automata approach coupled with governing equations for cavity nucleation and growth was developed to predict the size and distribution of cavities. Different growth mechanisms including diffusion and strain-controlled processes were taken into account and also, the coalescence phenomenon and the corresponding growth rate were considered in the model. The creep experiments were conducted on AA5052 under different temperatures and applied stresses such as 15 MPa at 300 °C, 20 MPa at 300 °C and 30 MPa at 270 °C for providing essential data points. Afterwards, the optical metallography and the scanning electron microscopy were performed to characterize the cavity size and distribution. The obtained results were then used to determine material constants and validate the simulation outcomes and a reasonable consistency was found between the predictions and experimental data. It was found that the strain-controlled growth is the dominant mechanism for strains larger than 0.04 while the coalescence of cavities might be significant when cavity volume fraction is higher than 0.5%. The simulations showed that the large cavity radius was observed when growth rate due to coalescence was implemented in the model.

Keywords

• Creep-cavitation
• Cavity coalescence
• Cellular automata
• Simulation
• Al–Mg alloy