Incremental forming is generally governed by the sine law and can not produce vertical walls. On the other hand, the incremental forming technology of a new style has been developed which is operated using a general-purpose elastomer base without instead of a blank support die. On this process, the step generated on the outer side of the blank sheet is moved by the bar tool like the motion of edge dislocation on the slip plane. In this operation, elements of material on the blank sheet can be delivered to the product by the bar tool going around the product. This means that this process can build a vertical wall by getting out of the sine law. By applying this technology, we attempted to form vertical wall products simulating a battery case. Forming examination has been conducted using blank sheet of aluminum alloy 5052-O. As a result, the products were created successfully, and the deformation properties were observed. In addition, square and dodecagonal double tubes formed successfully by using this process.

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.

The effect of soaking conditions of ingots on the rate of recovery and recrystallization in a 1050 hot-rolled sheet during annealing at 350°C was investigated. The rate of recovery and recrystallization in no soaking and 600°C/8 h WQ (water quenching) was slower than that of 450°C/8 h FC (furnace cooling). Many solute impurities (Fe, Si), which were contained in no soaking and 600°C/8 h WQ cause the delay of recovery and recrystallization. Particularly, in no soaking, no precipitation was observed within grains of the ingot and the hot-rolled sheet. On the other hand, in 450°C/8 h FC, the recovery and recrystallization is too fast. Fine granular precipitates with less than 0.1 µm in diameter were observed and solute impurities were few in the ingot and the hot-rolled sheet. The pinning of sub-grain boundaries by these fine precipitates was not observed. The normalized change of Vickers hardness and electrical resistivity was divided into a recovery reaction and a recrystallization one respectively by a new developed rate equation. The role of impurities in the recovery and recrystallization was explained and made clear by the obtained values of parameters in this equation.