Strain strengthening and structure formation during rhenium cold rolling

With the aim of developing a more perfect technology of rolling a study was made of the deformability, structure and strengthening of sintered metal and cast rhenium of technical purity in the course of cold-rolling a strip to a thickness of 0.01-0.02 mm and of its softening during annealing in the temperature range of 1000-1600 deg C in vacuum of 1x10-4 mm of mercury. The variation in microhardness served as an indicator of the degree of strengthening. It has been established that the ductility of annealed cast rhenium is about 30% higher than that of sintered metal rhenium. The relationship between strengthening and the degree of cold deformation and softening during annealing is similar for both cast and sintered metal rhenium. A total drafting between intermediate annealing is permissible for cast rhenium up to 60% and for sintered metal rhenium up to 40%. Softening, until initial hardness is achieved, takes place during annealing in the temperature range of 1500-1600 deg C. The prevalent deformation mechanism (slipping or twinning) depends both on the method of rhenium production and on the thickness of the strip to be rolled