Micromechanical behavior study of forged 7050 aluminum alloy by microindentation

In order to investigate the micromechanical behavior of forged 7050 aluminum alloy with different heat treatment conditions, microindentation experiments of 7050-T7451 and 7050-T7452 were performed with various maximum indentation loads and various loading speeds. A non-destructive instrumental approach was applied to indicate mechanical properties such as Young’s modulus E, microhardness H, initial yield stress σy and strain hardening exponent n using the available experimental indentation P–h curves from the microindentation tests. The experimental results revealed that loading speed exerted little influence on measurement of E and H. E decreased rapidly because of the indentation damage accumulation, and H decreased with the increase of indentation load, which showed strong indentation size effects. Dimensionless functions П1 and П2 were used to describe the plasticity constitutive equations and revealed that the heat treatment conditions influenced the micromechanical properties. H and σy tested from the microindentation of 7050-T7451 were higher than those of 7050-T7452, and microindentation plasticity constitutive equations were obtained by using Hookean elastic and power-law plastic stress–strain relation equations, which were verified by finite element method (FEM) simulation well.