Water-based lubricants with different fractions of TiO₂ nanoparticles ranging from 1.0 to 9.0 wt.% were utilized to study the lubrication mechanisms during micro rolling tests and the tribological behaviour of nanolubricants during the micro rolling of copper foils. The results indicate that the application of TiO₂ nanolubricants remarkably improves the surface quality of rolled copper foils during rolling processes. For lubricants with inadequate TiO₂ nanoparticles, it is found that few TiO₂ nanoparticles enter the contact regions between the rolls and foils, causing insufficient lubrication during rolling processes. Instead, for lubricants with excessive TiO₂ nanoparticles, obvious agglomeration occurs at the contact regions and promotes the generation of voids on the surface of the rolled foils, thereby deteriorating the surface quality of the rolled copper foils. In addition, it is found that the surface quality of rolled foils is improved by utilizing a large reduction ratio. Overall, the fraction of 3.0 wt.% TiO₂ nanolubricants is optimal to improve the lubrication conditions at the contact regions, thereby improving the surface quality of the rolled copper foils.

Systematic study on the microstructural evolution and mechanical properties of ferritic stainless steel (FSS) 430 with different annealing processes were carried out in the present work. The results show that microstructural refinement can be achieved by optimization of annealing processes, improving elongation, yield strength and tensile strength of FSS 430. An optimal annealing temperature of 950 ℃ is found with better homogeneity and enhanced mechanical properties among the cold-rolled and annealed FSSs. During annealing processes, the fraction of high angle grain boundaries of FSS 430 annealed at 950 ℃ is found to be the highest, indicating that a homogeneous microstructure with high recrystallization rate is formed inside the FSS 430 strips. In addition, high fraction of the hard grains (SF < 0.4) and low fraction of the soft grains are found inside FSS 430 annealed at 950 ℃, improving the plasticity of material. Overall, the optimization of annealing processes benefits the microstructural refinement of FSS and thereby improving the mechanical properties of materials.