2017 年 67 巻 7 号 p. 277-283
The microstructural evolution and changes in 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 ΣΔε=6 showed the yield strength of 252 MPa and the ultimate tensile strength of 282 MPa. MDFing evolved unique deformation texture at 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 288 MPa yield strength and 313 MPa ultimate tensile strength with 18.9% plastic strain to failure. The MDFing and subsequent aging succesfully produced homogeneous ultrafine-grained structure with average (sub)grain size of 220 nm.