Effect of pre-deformation on the mechanical properties of pre-aging AA7093

Abstract To improve the mechanical properties of T6 AA7093, this work investigated the effect of 4% pre-stretching on mechanical properties of the 20 min pre-aging AA7093. The results show that after taking 20 min pre-aging + 4% pre-stretching treatment, the hardness of AA7093 reached the peak after taking 9 hours aging. The yield strength and ultimate tensile strength of the pre-aging + pre-stretching + re-aging AA7093 are 631 MPa and 665 MPa, respectively. Comparing with T6 AA7093, the increase of yield strength and ultimate tensile strength are 75 MPa and 29 MPa, respectively. Kinetic analysis of DSC shows that the activation energy of precipitates in T6 and pre-aging and pre-aging + pre-stretching AA7093 alloys are 216.6 kJ/mol and 129.6 kJ/mol, respectively, this results in easier nucleation and growth of precipitates after pre-deformation. TEM shows a lot of precipitates generated on dislocations in pre-aging + pre-stretching + re-aging alloy, a lot of dislocation plugs generated by pre-deformation and precipitates will impede dislocations slip is the main reason that the yield strength of it is higher than T6 AA7093.