Ultrafine grained (UFG) materials have attracted a significant scientific interest due to their high mechanical strength resulted from their small (typically below 1 um) grains. However, their wider use in industry is restricted by their limited ductility and thermal stability. Low ductility creates problems with further metal forming procedures while low thermal stability results in  the lack of a reliable welding processes, which would allow to maintaing their high mechanical strength. The aim of this communication is to discuss the possibility of improving formability as well as obtaining good quality joints in UFG aluminium plates processed by Incremental Equal Channel Angular Pressing (I-ECAP) up to 8 passes.
From the post-processing point of you, the major advantage of I-ECAP processed plates is their homogenous microstructure, as a result of which the planar anisotropy is reduced almost to 0 while the mean anisotropy remains almost identical to that of the initial material. It was demonstrated that the forming ability was comparable to traditional CG material. Even more, the ductility and formability can be substantially increased by implementing proper strain rate and temperature of deformation process without excessive grain growth [1,2].
For joining, two technologies were proposed, i.e. Friction Stir Welding (FSW) and Electron Beam Welding (EBW). In both cases good quality joints without voids and pores were obtained. Although a decline in mechanical strength was observed in the joints, the results are of high interest. For FSW, a slight grain growth occurred in the stir zone, but the strength of joints is still higher than those for CG sample [3]. For EBW, the results were comparable to those obtained using solid-state welding, but with a significant advantage of narrower fusion- and heat-affected zones [4].

References
[1] M. Ciemiorek et al. Mater. Sci. Eng. A, 2022, 831, 142202.
[2] M. Ciemiorek et al. Archiv. Civ. Mech. Eng., 2022, 22, 169
[3] M. Orlowska et al. Mater. Sci. Eng. A, 2020, 777, 139076.
[4] M. Orlowska et al. Metall. Mater. Trans. A, 2022, 52, 18.