Yield strength modeling of an Al-Cu-Li alloy through circle rolling and flow stress superposition approach

In the present work, the shear stress required to move a dislocation through an array of randomly distributed T1 precipitates (Al2CuLi), forest dislocations and solutes was computed using the circle rolling method. The evolution of shear stress as a function of swept area was determined to calculate the shear resistance of T1 precipitates, forest dislocations and solutes for different ageing conditions. The inputs for the circle rolling simulations, such as the critical breaking angle of the obstacles, were obtained by performing detailed microstructural analysis at different length scales to estimate forest dislocation density, diameter, thickness, and number density of T1 precipitates. The individual shear resistance of precipitates, dislocations and solutes were suitably superimposed using a flow stress addition law, where the superposition exponent is dependent on the critical breaking angles of the T1 precipitates, forest dislocations and solutes. The present approach outperforms previous models based on the linear superposition of strengthening components in predicting the yield strength evolution of AA 2195 alloy as a function of pre-strain.