Microstructural evolution and enhanced mechanical properties by multi-directional forging and aging of 6000 series aluminum alloy

Abstract

Microstructural evolution and changes in the mechanical properties of 6000 series aluminum alloys during multi-directional forging (MDFing) and artificial aging were systematically investigated. The strength gradually increased with increasing cumulative strain. The MDFed sample up to a cumulative strain of ∑Δε = 6 showed a yield strength of 252 MPa and an ultimate tensile strength (UTS) of 282 MPa. MDFing evolved a unique deformation texture at a higher cumulative strain region. Artificial aging at 373 K and 393 K after MDFing caused moderate hardening, although softening took place over 423 K without any obvious hardening. The artificially aged sample at 393 K for 100 ks after MDFing exhibited well-balanced mechanical properties of a 288 MPa yield strength and a 313 MPa UTS with an 18.9% plastic strain to failure. The MDFing and subsequent aging succesfully produced a homogeneous ultrafine-grained microstructure with an average (sub)grain size of 220 nm.