Analysis of Severe Plastic Deformation and Recrystallization of Cu under Instantaneous Extrusion and High Speed Friction

A new experimental project was adopted for the special hot-work of pure Cu, which used the execrable condition of high-temperature and high-pressure environment in bore of artillery. Specimen of Cu was prepared from rotating band of sand projectile which had been shot out. Microstructure of Cu after instantaneous extrusion and high speed friction were observed by scanning electron microscopy (SEM). Severe plastic deformation (SPD) and recrystallization phenomena were researched. The analysis results are as follows. At the beginning of SPD, under the instantaneous compression, the surface layer of metal became fibrous tissue with the phenomena of work-hardening. Many oblique strip grains appeared between equiaxed grains and fibrous tissue. With the continuous plastic deformation, temperature of metal improved rapidly under the high speed friction. Recrystallization occurred on the outermost part of fibrous tissue due to heating, so sub-grains gradually became homogeneous equiaxed grains. In addition, SPD had little effect to the inner structure, which is full of equiaxed grains still. All above work could support the research of microstructure of Cu on certain extreme particular environment.