Investigation Of Grain Refinement And Mechanical Properties Of Commercial Pure Aluminum After Rolling

Compared with the traditional coarse grain materials, ultrafine-grained materials (grain size in the range0.1～1μm) have excellent physical and mechanical properties, which is one of the most interesting topic in the material field and has a variety of application. Rolling, which is one of the severely plastic deformation technologies, has the strong ability to induce grain refinement. In this paper, the processing of ultrafine grain, severely plastic deformation technology and rolling method have been introduced. Many researches have been conducted the grain refinement of pure aluminum by rolling method. The mechanical properties and microstructures of the ultrafine-grained pure aluminum prepared by severely plastic deformation technology were studied by using metallographic microscope, scanning electron microscope and transmission electron microscope. Room temperature tensile and microhardness testing were performed. The results as follows:1. Grain refinement of the pure aluminum samples can be realized under different rolling distortions. The grain size of the3mm and lmm rolling samples is about900nm,500nm, respectively.2. lmm rolling sample was annealed at150℃for30minutes. Compared the as cold-rolled state, the yield strength improved obviously, while ductility has been decreased after annealing, which is reffered to as a kind of annealing strengthen phenomenon. In term of the amount of rolling, the annealing temperature and the annealing time, Parameters to obtain strengthening effect were investigated, It is found that:1) As the amount of the rolling decreased, the strengthening effect decrease, the annealing strengthening of the lmm rolling sample is more pronounced than that of the3mm rolling sample.2) In terms of the annealing at150℃for5-120minutes tests, the lmm rolling sample changes from annealing strengthening (1-60minutes) to annealing softening (60-120minutes), and the best annealing time is30minutes at this annealing temperature.3) For the lmm rolling sample annealing at150-250℃for30minutes, annealing strengthening (150℃) changes to annealing softening (250℃), and the best annealing temperature is150℃ 3. There are differences in mechanical properties of the pure aluminum samples prepared under the same distortion and different rolling directions, and the latter one has the better yield strength.4. Annealed for30minutes at150and250℃, the3mm double-direction rolling sample transform from the annealing strengthening to annealing softening to a certain degree. And for the certain time, the strength and hardness decrease obviously with the increase of the temperature.5. The primary pure aluminum sample was subjected to by accumulative roll bonding. The strength of samples after accumulative roll bonding improved significantly, and the ductility was decreased obviously.