Study On Deformation Behavior Of Metal Strip And Its Microstructural Evolution During Shear-rolling Process

The properties of metal depend on its grain size. Mechanical strength and hardness will increase with the decreasing of grain size. Therefore, grain refinement is always an effective method of improving comprehensive performance of metal material. At present, people have been able to prepare ultrafine-grained materials. Methods to prepare ultrafine-grained matcrials are numerous, of which severe plastic deformation gets more and more focus because of its merits of preparing dense bulk material with simple craft and little cost. However, due to the small size of the deformation device, it is difficult to realize the scale of production. This plastic deformation theory provides a good theoretical basis to grain refinement and performance improvement. The method used in this paper is shear-rolling deformation, and this paper stuied on the shear-rolling deformation behavior and microstructure evolution of matal strip, explored the feasibility of scale of production of fine-grained materials, and alse studied how process conditions will affect the average grain size and grain morphology of materials.This paper selected the pure copper strip with thickness of4.00mm, and purity of99.95%as the sample deformation material. It would be reduced in thickness to1.90mm by two passes rolling deformation, heating treatment after each pass rolling deformation, to eliminate work-hardening and obtain shear-rolling strip. By stuying on the shear-rolling deformation behavior and microstructure evolution of matal strip can obtain the variation of strip thickness and grain size. The results are as follows:When the shear-rolling deformation angle is70°, shear-rolling pass is16passes (annealing once after every four passes) heat treatment temperature is360℃, heat treatment time is6minute, grain morphology is best. The average grain size is4.58μm. The average grain size that shear-rolling deformation without turning when every pass shear-rolling deformation is finished is5.56μm; the average grain size that shear-rolling deformation with turning when four pass shear-rolling deformation is finished is4.85μm. Through shear-rolling deformation, the thickness of pure copper strip is increased, then through rolling deformation, the thickness of pure copper strip is restoration; with the increase of shear-rolling passes, thickness of the phenomenon is increasingly no obcious, until thickness is no increased. This method has a certain extent to make grain refinement, after16shear-rolling passes, the grain size is not smaller. The method is suitable for fine-material production that grain size between5～10μm.